socket.io.js

/*!
 * Socket.IO v4.4.1
 * (c) 2014-2022 Guillermo Rauch
 * Released under the MIT License.
 */
(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  typeof define === 'function' && define.amd ? define(factory) :
  (global = typeof globalThis !== 'undefined' ? globalThis : global || self, global.io = factory());
})(this, (function () { 'use strict';

  function _typeof(obj) {
    "@babel/helpers - typeof";

    if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") {
      _typeof = function (obj) {
        return typeof obj;
      };
    } else {
      _typeof = function (obj) {
        return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
      };
    }

    return _typeof(obj);
  }

  function _classCallCheck(instance, Constructor) {
    if (!(instance instanceof Constructor)) {
      throw new TypeError("Cannot call a class as a function");
    }
  }

  function _defineProperties(target, props) {
    for (var i = 0; i < props.length; i++) {
      var descriptor = props[i];
      descriptor.enumerable = descriptor.enumerable || false;
      descriptor.configurable = true;
      if ("value" in descriptor) descriptor.writable = true;
      Object.defineProperty(target, descriptor.key, descriptor);
    }
  }

  function _createClass(Constructor, protoProps, staticProps) {
    if (protoProps) _defineProperties(Constructor.prototype, protoProps);
    if (staticProps) _defineProperties(Constructor, staticProps);
    return Constructor;
  }

  function _extends() {
    _extends = Object.assign || function (target) {
      for (var i = 1; i < arguments.length; i++) {
        var source = arguments[i];

        for (var key in source) {
          if (Object.prototype.hasOwnProperty.call(source, key)) {
            target[key] = source[key];
          }
        }
      }

      return target;
    };

    return _extends.apply(this, arguments);
  }

  function _inherits(subClass, superClass) {
    if (typeof superClass !== "function" && superClass !== null) {
      throw new TypeError("Super expression must either be null or a function");
    }

    subClass.prototype = Object.create(superClass && superClass.prototype, {
      constructor: {
        value: subClass,
        writable: true,
        configurable: true
      }
    });
    if (superClass) _setPrototypeOf(subClass, superClass);
  }

  function _getPrototypeOf(o) {
    _getPrototypeOf = Object.setPrototypeOf ? Object.getPrototypeOf : function _getPrototypeOf(o) {
      return o.__proto__ || Object.getPrototypeOf(o);
    };
    return _getPrototypeOf(o);
  }

  function _setPrototypeOf(o, p) {
    _setPrototypeOf = Object.setPrototypeOf || function _setPrototypeOf(o, p) {
      o.__proto__ = p;
      return o;
    };

    return _setPrototypeOf(o, p);
  }

  function _isNativeReflectConstruct() {
    if (typeof Reflect === "undefined" || !Reflect.construct) return false;
    if (Reflect.construct.sham) return false;
    if (typeof Proxy === "function") return true;

    try {
      Boolean.prototype.valueOf.call(Reflect.construct(Boolean, [], function () {}));
      return true;
    } catch (e) {
      return false;
    }
  }

  function _assertThisInitialized(self) {
    if (self === void 0) {
      throw new ReferenceError("this hasn't been initialised - super() hasn't been called");
    }

    return self;
  }

  function _possibleConstructorReturn(self, call) {
    if (call && (typeof call === "object" || typeof call === "function")) {
      return call;
    } else if (call !== void 0) {
      throw new TypeError("Derived constructors may only return object or undefined");
    }

    return _assertThisInitialized(self);
  }

  function _createSuper(Derived) {
    var hasNativeReflectConstruct = _isNativeReflectConstruct();

    return function _createSuperInternal() {
      var Super = _getPrototypeOf(Derived),
          result;

      if (hasNativeReflectConstruct) {
        var NewTarget = _getPrototypeOf(this).constructor;

        result = Reflect.construct(Super, arguments, NewTarget);
      } else {
        result = Super.apply(this, arguments);
      }

      return _possibleConstructorReturn(this, result);
    };
  }

  function _superPropBase(object, property) {
    while (!Object.prototype.hasOwnProperty.call(object, property)) {
      object = _getPrototypeOf(object);
      if (object === null) break;
    }

    return object;
  }

  function _get(target, property, receiver) {
    if (typeof Reflect !== "undefined" && Reflect.get) {
      _get = Reflect.get;
    } else {
      _get = function _get(target, property, receiver) {
        var base = _superPropBase(target, property);

        if (!base) return;
        var desc = Object.getOwnPropertyDescriptor(base, property);

        if (desc.get) {
          return desc.get.call(receiver);
        }

        return desc.value;
      };
    }

    return _get(target, property, receiver || target);
  }

  function _unsupportedIterableToArray(o, minLen) {
    if (!o) return;
    if (typeof o === "string") return _arrayLikeToArray(o, minLen);
    var n = Object.prototype.toString.call(o).slice(8, -1);
    if (n === "Object" && o.constructor) n = o.constructor.name;
    if (n === "Map" || n === "Set") return Array.from(o);
    if (n === "Arguments" || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(n)) return _arrayLikeToArray(o, minLen);
  }

  function _arrayLikeToArray(arr, len) {
    if (len == null || len > arr.length) len = arr.length;

    for (var i = 0, arr2 = new Array(len); i < len; i++) arr2[i] = arr[i];

    return arr2;
  }

  function _createForOfIteratorHelper(o, allowArrayLike) {
    var it = typeof Symbol !== "undefined" && o[Symbol.iterator] || o["@@iterator"];

    if (!it) {
      if (Array.isArray(o) || (it = _unsupportedIterableToArray(o)) || allowArrayLike && o && typeof o.length === "number") {
        if (it) o = it;
        var i = 0;

        var F = function () {};

        return {
          s: F,
          n: function () {
            if (i >= o.length) return {
              done: true
            };
            return {
              done: false,
              value: o[i++]
            };
          },
          e: function (e) {
            throw e;
          },
          f: F
        };
      }

      throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method.");
    }

    var normalCompletion = true,
        didErr = false,
        err;
    return {
      s: function () {
        it = it.call(o);
      },
      n: function () {
        var step = it.next();
        normalCompletion = step.done;
        return step;
      },
      e: function (e) {
        didErr = true;
        err = e;
      },
      f: function () {
        try {
          if (!normalCompletion && it.return != null) it.return();
        } finally {
          if (didErr) throw err;
        }
      }
    };
  }

  /**
   * Parses an URI
   *
   * @author Steven Levithan <stevenlevithan.com> (MIT license)
   * @api private
   */
  var re = /^(?:(?![^:@]+:[^:@\/]*@)(http|https|ws|wss):\/\/)?((?:(([^:@]*)(?::([^:@]*))?)?@)?((?:[a-f0-9]{0,4}:){2,7}[a-f0-9]{0,4}|[^:\/?#]*)(?::(\d*))?)(((\/(?:[^?#](?![^?#\/]*\.[^?#\/.]+(?:[?#]|$)))*\/?)?([^?#\/]*))(?:\?([^#]*))?(?:#(.*))?)/;
  var parts = ['source', 'protocol', 'authority', 'userInfo', 'user', 'password', 'host', 'port', 'relative', 'path', 'directory', 'file', 'query', 'anchor'];

  var parseuri = function parseuri(str) {
    var src = str,
        b = str.indexOf('['),
        e = str.indexOf(']');

    if (b != -1 && e != -1) {
      str = str.substring(0, b) + str.substring(b, e).replace(/:/g, ';') + str.substring(e, str.length);
    }

    var m = re.exec(str || ''),
        uri = {},
        i = 14;

    while (i--) {
      uri[parts[i]] = m[i] || '';
    }

    if (b != -1 && e != -1) {
      uri.source = src;
      uri.host = uri.host.substring(1, uri.host.length - 1).replace(/;/g, ':');
      uri.authority = uri.authority.replace('[', '').replace(']', '').replace(/;/g, ':');
      uri.ipv6uri = true;
    }

    uri.pathNames = pathNames(uri, uri['path']);
    uri.queryKey = queryKey(uri, uri['query']);
    return uri;
  };

  function pathNames(obj, path) {
    var regx = /\/{2,9}/g,
        names = path.replace(regx, "/").split("/");

    if (path.substr(0, 1) == '/' || path.length === 0) {
      names.splice(0, 1);
    }

    if (path.substr(path.length - 1, 1) == '/') {
      names.splice(names.length - 1, 1);
    }

    return names;
  }

  function queryKey(uri, query) {
    var data = {};
    query.replace(/(?:^|&)([^&=]*)=?([^&]*)/g, function ($0, $1, $2) {
      if ($1) {
        data[$1] = $2;
      }
    });
    return data;
  }

  /**
   * URL parser.
   *
   * @param uri - url
   * @param path - the request path of the connection
   * @param loc - An object meant to mimic window.location.
   *        Defaults to window.location.
   * @public
   */

  function url(uri) {
    var path = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : "";
    var loc = arguments.length > 2 ? arguments[2] : undefined;
    var obj = uri; // default to window.location

    loc = loc || typeof location !== "undefined" && location;
    if (null == uri) uri = loc.protocol + "//" + loc.host; // relative path support

    if (typeof uri === "string") {
      if ("/" === uri.charAt(0)) {
        if ("/" === uri.charAt(1)) {
          uri = loc.protocol + uri;
        } else {
          uri = loc.host + uri;
        }
      }

      if (!/^(https?|wss?):\/\//.test(uri)) {
        if ("undefined" !== typeof loc) {
          uri = loc.protocol + "//" + uri;
        } else {
          uri = "https://" + uri;
        }
      } // parse


      obj = parseuri(uri);
    } // make sure we treat `localhost:80` and `localhost` equally


    if (!obj.port) {
      if (/^(http|ws)$/.test(obj.protocol)) {
        obj.port = "80";
      } else if (/^(http|ws)s$/.test(obj.protocol)) {
        obj.port = "443";
      }
    }

    obj.path = obj.path || "/";
    var ipv6 = obj.host.indexOf(":") !== -1;
    var host = ipv6 ? "[" + obj.host + "]" : obj.host; // define unique id

    obj.id = obj.protocol + "://" + host + ":" + obj.port + path; // define href

    obj.href = obj.protocol + "://" + host + (loc && loc.port === obj.port ? "" : ":" + obj.port);
    return obj;
  }

  var hasCors = {exports: {}};

  /**
   * Module exports.
   *
   * Logic borrowed from Modernizr:
   *
   *   - https://github.com/Modernizr/Modernizr/blob/master/feature-detects/cors.js
   */

  try {
    hasCors.exports = typeof XMLHttpRequest !== 'undefined' && 'withCredentials' in new XMLHttpRequest();
  } catch (err) {
    // if XMLHttp support is disabled in IE then it will throw
    // when trying to create
    hasCors.exports = false;
  }

  var hasCORS = hasCors.exports;

  var globalThis = (function () {
    if (typeof self !== "undefined") {
      return self;
    } else if (typeof window !== "undefined") {
      return window;
    } else {
      return Function("return this")();
    }
  })();

  // browser shim for xmlhttprequest module
  function XMLHttpRequest$1 (opts) {
    var xdomain = opts.xdomain; // XMLHttpRequest can be disabled on IE

    try {
      if ("undefined" !== typeof XMLHttpRequest && (!xdomain || hasCORS)) {
        return new XMLHttpRequest();
      }
    } catch (e) {}

    if (!xdomain) {
      try {
        return new globalThis[["Active"].concat("Object").join("X")]("Microsoft.XMLHTTP");
      } catch (e) {}
    }
  }

  function pick(obj) {
    for (var _len = arguments.length, attr = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
      attr[_key - 1] = arguments[_key];
    }

    return attr.reduce(function (acc, k) {
      if (obj.hasOwnProperty(k)) {
        acc[k] = obj[k];
      }

      return acc;
    }, {});
  } // Keep a reference to the real timeout functions so they can be used when overridden

  var NATIVE_SET_TIMEOUT = setTimeout;
  var NATIVE_CLEAR_TIMEOUT = clearTimeout;
  function installTimerFunctions(obj, opts) {
    if (opts.useNativeTimers) {
      obj.setTimeoutFn = NATIVE_SET_TIMEOUT.bind(globalThis);
      obj.clearTimeoutFn = NATIVE_CLEAR_TIMEOUT.bind(globalThis);
    } else {
      obj.setTimeoutFn = setTimeout.bind(globalThis);
      obj.clearTimeoutFn = clearTimeout.bind(globalThis);
    }
  }

  /**
   * Expose `Emitter`.
   */

  var Emitter_1 = Emitter;
  /**
   * Initialize a new `Emitter`.
   *
   * @api public
   */

  function Emitter(obj) {
    if (obj) return mixin(obj);
  }
  /**
   * Mixin the emitter properties.
   *
   * @param {Object} obj
   * @return {Object}
   * @api private
   */


  function mixin(obj) {
    for (var key in Emitter.prototype) {
      obj[key] = Emitter.prototype[key];
    }

    return obj;
  }
  /**
   * Listen on the given `event` with `fn`.
   *
   * @param {String} event
   * @param {Function} fn
   * @return {Emitter}
   * @api public
   */


  Emitter.prototype.on = Emitter.prototype.addEventListener = function (event, fn) {
    this._callbacks = this._callbacks || {};
    (this._callbacks['$' + event] = this._callbacks['$' + event] || []).push(fn);
    return this;
  };
  /**
   * Adds an `event` listener that will be invoked a single
   * time then automatically removed.
   *
   * @param {String} event
   * @param {Function} fn
   * @return {Emitter}
   * @api public
   */


  Emitter.prototype.once = function (event, fn) {
    function on() {
      this.off(event, on);
      fn.apply(this, arguments);
    }

    on.fn = fn;
    this.on(event, on);
    return this;
  };
  /**
   * Remove the given callback for `event` or all
   * registered callbacks.
   *
   * @param {String} event
   * @param {Function} fn
   * @return {Emitter}
   * @api public
   */


  Emitter.prototype.off = Emitter.prototype.removeListener = Emitter.prototype.removeAllListeners = Emitter.prototype.removeEventListener = function (event, fn) {
    this._callbacks = this._callbacks || {}; // all

    if (0 == arguments.length) {
      this._callbacks = {};
      return this;
    } // specific event


    var callbacks = this._callbacks['$' + event];
    if (!callbacks) return this; // remove all handlers

    if (1 == arguments.length) {
      delete this._callbacks['$' + event];
      return this;
    } // remove specific handler


    var cb;

    for (var i = 0; i < callbacks.length; i++) {
      cb = callbacks[i];

      if (cb === fn || cb.fn === fn) {
        callbacks.splice(i, 1);
        break;
      }
    } // Remove event specific arrays for event types that no
    // one is subscribed for to avoid memory leak.


    if (callbacks.length === 0) {
      delete this._callbacks['$' + event];
    }

    return this;
  };
  /**
   * Emit `event` with the given args.
   *
   * @param {String} event
   * @param {Mixed} ...
   * @return {Emitter}
   */


  Emitter.prototype.emit = function (event) {
    this._callbacks = this._callbacks || {};
    var args = new Array(arguments.length - 1),
        callbacks = this._callbacks['$' + event];

    for (var i = 1; i < arguments.length; i++) {
      args[i - 1] = arguments[i];
    }

    if (callbacks) {
      callbacks = callbacks.slice(0);

      for (var i = 0, len = callbacks.length; i < len; ++i) {
        callbacks[i].apply(this, args);
      }
    }

    return this;
  }; // alias used for reserved events (protected method)


  Emitter.prototype.emitReserved = Emitter.prototype.emit;
  /**
   * Return array of callbacks for `event`.
   *
   * @param {String} event
   * @return {Array}
   * @api public
   */

  Emitter.prototype.listeners = function (event) {
    this._callbacks = this._callbacks || {};
    return this._callbacks['$' + event] || [];
  };
  /**
   * Check if this emitter has `event` handlers.
   *
   * @param {String} event
   * @return {Boolean}
   * @api public
   */


  Emitter.prototype.hasListeners = function (event) {
    return !!this.listeners(event).length;
  };

  var PACKET_TYPES = Object.create(null); // no Map = no polyfill

  PACKET_TYPES["open"] = "0";
  PACKET_TYPES["close"] = "1";
  PACKET_TYPES["ping"] = "2";
  PACKET_TYPES["pong"] = "3";
  PACKET_TYPES["message"] = "4";
  PACKET_TYPES["upgrade"] = "5";
  PACKET_TYPES["noop"] = "6";
  var PACKET_TYPES_REVERSE = Object.create(null);
  Object.keys(PACKET_TYPES).forEach(function (key) {
    PACKET_TYPES_REVERSE[PACKET_TYPES[key]] = key;
  });
  var ERROR_PACKET = {
    type: "error",
    data: "parser error"
  };

  var withNativeBlob$1 = typeof Blob === "function" || typeof Blob !== "undefined" && Object.prototype.toString.call(Blob) === "[object BlobConstructor]";
  var withNativeArrayBuffer$2 = typeof ArrayBuffer === "function"; // ArrayBuffer.isView method is not defined in IE10

  var isView$1 = function isView(obj) {
    return typeof ArrayBuffer.isView === "function" ? ArrayBuffer.isView(obj) : obj && obj.buffer instanceof ArrayBuffer;
  };

  var encodePacket = function encodePacket(_ref, supportsBinary, callback) {
    var type = _ref.type,
        data = _ref.data;

    if (withNativeBlob$1 && data instanceof Blob) {
      if (supportsBinary) {
        return callback(data);
      } else {
        return encodeBlobAsBase64(data, callback);
      }
    } else if (withNativeArrayBuffer$2 && (data instanceof ArrayBuffer || isView$1(data))) {
      if (supportsBinary) {
        return callback(data);
      } else {
        return encodeBlobAsBase64(new Blob([data]), callback);
      }
    } // plain string


    return callback(PACKET_TYPES[type] + (data || ""));
  };

  var encodeBlobAsBase64 = function encodeBlobAsBase64(data, callback) {
    var fileReader = new FileReader();

    fileReader.onload = function () {
      var content = fileReader.result.split(",")[1];
      callback("b" + content);
    };

    return fileReader.readAsDataURL(data);
  };

  /*
   * base64-arraybuffer 1.0.1 <https://github.com/niklasvh/base64-arraybuffer>
   * Copyright (c) 2021 Niklas von Hertzen <https://hertzen.com>
   * Released under MIT License
   */
  var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'; // Use a lookup table to find the index.

  var lookup$1 = typeof Uint8Array === 'undefined' ? [] : new Uint8Array(256);

  for (var i$1 = 0; i$1 < chars.length; i$1++) {
    lookup$1[chars.charCodeAt(i$1)] = i$1;
  }

  var decode$1 = function decode(base64) {
    var bufferLength = base64.length * 0.75,
        len = base64.length,
        i,
        p = 0,
        encoded1,
        encoded2,
        encoded3,
        encoded4;

    if (base64[base64.length - 1] === '=') {
      bufferLength--;

      if (base64[base64.length - 2] === '=') {
        bufferLength--;
      }
    }

    var arraybuffer = new ArrayBuffer(bufferLength),
        bytes = new Uint8Array(arraybuffer);

    for (i = 0; i < len; i += 4) {
      encoded1 = lookup$1[base64.charCodeAt(i)];
      encoded2 = lookup$1[base64.charCodeAt(i + 1)];
      encoded3 = lookup$1[base64.charCodeAt(i + 2)];
      encoded4 = lookup$1[base64.charCodeAt(i + 3)];
      bytes[p++] = encoded1 << 2 | encoded2 >> 4;
      bytes[p++] = (encoded2 & 15) << 4 | encoded3 >> 2;
      bytes[p++] = (encoded3 & 3) << 6 | encoded4 & 63;
    }

    return arraybuffer;
  };

  var withNativeArrayBuffer$1 = typeof ArrayBuffer === "function";

  var decodePacket = function decodePacket(encodedPacket, binaryType) {
    if (typeof encodedPacket !== "string") {
      return {
        type: "message",
        data: mapBinary(encodedPacket, binaryType)
      };
    }

    var type = encodedPacket.charAt(0);

    if (type === "b") {
      return {
        type: "message",
        data: decodeBase64Packet(encodedPacket.substring(1), binaryType)
      };
    }

    var packetType = PACKET_TYPES_REVERSE[type];

    if (!packetType) {
      return ERROR_PACKET;
    }

    return encodedPacket.length > 1 ? {
      type: PACKET_TYPES_REVERSE[type],
      data: encodedPacket.substring(1)
    } : {
      type: PACKET_TYPES_REVERSE[type]
    };
  };

  var decodeBase64Packet = function decodeBase64Packet(data, binaryType) {
    if (withNativeArrayBuffer$1) {
      var decoded = decode$1(data);
      return mapBinary(decoded, binaryType);
    } else {
      return {
        base64: true,
        data: data
      }; // fallback for old browsers
    }
  };

  var mapBinary = function mapBinary(data, binaryType) {
    switch (binaryType) {
      case "blob":
        return data instanceof ArrayBuffer ? new Blob([data]) : data;

      case "arraybuffer":
      default:
        return data;
      // assuming the data is already an ArrayBuffer
    }
  };

  var SEPARATOR = String.fromCharCode(30); // see https://en.wikipedia.org/wiki/Delimiter#ASCII_delimited_text

  var encodePayload = function encodePayload(packets, callback) {
    // some packets may be added to the array while encoding, so the initial length must be saved
    var length = packets.length;
    var encodedPackets = new Array(length);
    var count = 0;
    packets.forEach(function (packet, i) {
      // force base64 encoding for binary packets
      encodePacket(packet, false, function (encodedPacket) {
        encodedPackets[i] = encodedPacket;

        if (++count === length) {
          callback(encodedPackets.join(SEPARATOR));
        }
      });
    });
  };

  var decodePayload = function decodePayload(encodedPayload, binaryType) {
    var encodedPackets = encodedPayload.split(SEPARATOR);
    var packets = [];

    for (var i = 0; i < encodedPackets.length; i++) {
      var decodedPacket = decodePacket(encodedPackets[i], binaryType);
      packets.push(decodedPacket);

      if (decodedPacket.type === "error") {
        break;
      }
    }

    return packets;
  };

  var protocol$1 = 4;

  var Transport = /*#__PURE__*/function (_Emitter) {
    _inherits(Transport, _Emitter);

    var _super = _createSuper(Transport);

    /**
     * Transport abstract constructor.
     *
     * @param {Object} options.
     * @api private
     */
    function Transport(opts) {
      var _this;

      _classCallCheck(this, Transport);

      _this = _super.call(this);
      _this.writable = false;
      installTimerFunctions(_assertThisInitialized(_this), opts);
      _this.opts = opts;
      _this.query = opts.query;
      _this.readyState = "";
      _this.socket = opts.socket;
      return _this;
    }
    /**
     * Emits an error.
     *
     * @param {String} str
     * @return {Transport} for chaining
     * @api protected
     */


    _createClass(Transport, [{
      key: "onError",
      value: function onError(msg, desc) {
        var err = new Error(msg); // @ts-ignore

        err.type = "TransportError"; // @ts-ignore

        err.description = desc;

        _get(_getPrototypeOf(Transport.prototype), "emit", this).call(this, "error", err);

        return this;
      }
      /**
       * Opens the transport.
       *
       * @api public
       */

    }, {
      key: "open",
      value: function open() {
        if ("closed" === this.readyState || "" === this.readyState) {
          this.readyState = "opening";
          this.doOpen();
        }

        return this;
      }
      /**
       * Closes the transport.
       *
       * @api public
       */

    }, {
      key: "close",
      value: function close() {
        if ("opening" === this.readyState || "open" === this.readyState) {
          this.doClose();
          this.onClose();
        }

        return this;
      }
      /**
       * Sends multiple packets.
       *
       * @param {Array} packets
       * @api public
       */

    }, {
      key: "send",
      value: function send(packets) {
        if ("open" === this.readyState) {
          this.write(packets);
        }
      }
      /**
       * Called upon open
       *
       * @api protected
       */

    }, {
      key: "onOpen",
      value: function onOpen() {
        this.readyState = "open";
        this.writable = true;

        _get(_getPrototypeOf(Transport.prototype), "emit", this).call(this, "open");
      }
      /**
       * Called with data.
       *
       * @param {String} data
       * @api protected
       */

    }, {
      key: "onData",
      value: function onData(data) {
        var packet = decodePacket(data, this.socket.binaryType);
        this.onPacket(packet);
      }
      /**
       * Called with a decoded packet.
       *
       * @api protected
       */

    }, {
      key: "onPacket",
      value: function onPacket(packet) {
        _get(_getPrototypeOf(Transport.prototype), "emit", this).call(this, "packet", packet);
      }
      /**
       * Called upon close.
       *
       * @api protected
       */

    }, {
      key: "onClose",
      value: function onClose() {
        this.readyState = "closed";

        _get(_getPrototypeOf(Transport.prototype), "emit", this).call(this, "close");
      }
    }]);

    return Transport;
  }(Emitter_1);

  var alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_'.split(''),
      length = 64,
      map = {},
      seed = 0,
      i = 0,
      prev;
  /**
   * Return a string representing the specified number.
   *
   * @param {Number} num The number to convert.
   * @returns {String} The string representation of the number.
   * @api public
   */

  function encode(num) {
    var encoded = '';

    do {
      encoded = alphabet[num % length] + encoded;
      num = Math.floor(num / length);
    } while (num > 0);

    return encoded;
  }
  /**
   * Return the integer value specified by the given string.
   *
   * @param {String} str The string to convert.
   * @returns {Number} The integer value represented by the string.
   * @api public
   */


  function decode(str) {
    var decoded = 0;

    for (i = 0; i < str.length; i++) {
      decoded = decoded * length + map[str.charAt(i)];
    }

    return decoded;
  }
  /**
   * Yeast: A tiny growing id generator.
   *
   * @returns {String} A unique id.
   * @api public
   */


  function yeast() {
    var now = encode(+new Date());
    if (now !== prev) return seed = 0, prev = now;
    return now + '.' + encode(seed++);
  } //
  // Map each character to its index.
  //


  for (; i < length; i++) {
    map[alphabet[i]] = i;
  } //
  // Expose the `yeast`, `encode` and `decode` functions.
  //


  yeast.encode = encode;
  yeast.decode = decode;
  var yeast_1 = yeast;

  var parseqs = {};

  /**
   * Compiles a querystring
   * Returns string representation of the object
   *
   * @param {Object}
   * @api private
   */

  parseqs.encode = function (obj) {
    var str = '';

    for (var i in obj) {
      if (obj.hasOwnProperty(i)) {
        if (str.length) str += '&';
        str += encodeURIComponent(i) + '=' + encodeURIComponent(obj[i]);
      }
    }

    return str;
  };
  /**
   * Parses a simple querystring into an object
   *
   * @param {String} qs
   * @api private
   */


  parseqs.decode = function (qs) {
    var qry = {};
    var pairs = qs.split('&');

    for (var i = 0, l = pairs.length; i < l; i++) {
      var pair = pairs[i].split('=');
      qry[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1]);
    }

    return qry;
  };

  var Polling = /*#__PURE__*/function (_Transport) {
    _inherits(Polling, _Transport);

    var _super = _createSuper(Polling);

    function Polling() {
      var _this;

      _classCallCheck(this, Polling);

      _this = _super.apply(this, arguments);
      _this.polling = false;
      return _this;
    }
    /**
     * Transport name.
     */


    _createClass(Polling, [{
      key: "name",
      get: function get() {
        return "polling";
      }
      /**
       * Opens the socket (triggers polling). We write a PING message to determine
       * when the transport is open.
       *
       * @api private
       */

    }, {
      key: "doOpen",
      value: function doOpen() {
        this.poll();
      }
      /**
       * Pauses polling.
       *
       * @param {Function} callback upon buffers are flushed and transport is paused
       * @api private
       */

    }, {
      key: "pause",
      value: function pause(onPause) {
        var _this2 = this;

        this.readyState = "pausing";

        var pause = function pause() {
          _this2.readyState = "paused";
          onPause();
        };

        if (this.polling || !this.writable) {
          var total = 0;

          if (this.polling) {
            total++;
            this.once("pollComplete", function () {
              --total || pause();
            });
          }

          if (!this.writable) {
            total++;
            this.once("drain", function () {
              --total || pause();
            });
          }
        } else {
          pause();
        }
      }
      /**
       * Starts polling cycle.
       *
       * @api public
       */

    }, {
      key: "poll",
      value: function poll() {
        this.polling = true;
        this.doPoll();
        this.emit("poll");
      }
      /**
       * Overloads onData to detect payloads.
       *
       * @api private
       */

    }, {
      key: "onData",
      value: function onData(data) {
        var _this3 = this;

        var callback = function callback(packet) {
          // if its the first message we consider the transport open
          if ("opening" === _this3.readyState && packet.type === "open") {
            _this3.onOpen();
          } // if its a close packet, we close the ongoing requests


          if ("close" === packet.type) {
            _this3.onClose();

            return false;
          } // otherwise bypass onData and handle the message


          _this3.onPacket(packet);
        }; // decode payload


        decodePayload(data, this.socket.binaryType).forEach(callback); // if an event did not trigger closing

        if ("closed" !== this.readyState) {
          // if we got data we're not polling
          this.polling = false;
          this.emit("pollComplete");

          if ("open" === this.readyState) {
            this.poll();
          }
        }
      }
      /**
       * For polling, send a close packet.
       *
       * @api private
       */

    }, {
      key: "doClose",
      value: function doClose() {
        var _this4 = this;

        var close = function close() {
          _this4.write([{
            type: "close"
          }]);
        };

        if ("open" === this.readyState) {
          close();
        } else {
          // in case we're trying to close while
          // handshaking is in progress (GH-164)
          this.once("open", close);
        }
      }
      /**
       * Writes a packets payload.
       *
       * @param {Array} data packets
       * @param {Function} drain callback
       * @api private
       */

    }, {
      key: "write",
      value: function write(packets) {
        var _this5 = this;

        this.writable = false;
        encodePayload(packets, function (data) {
          _this5.doWrite(data, function () {
            _this5.writable = true;

            _this5.emit("drain");
          });
        });
      }
      /**
       * Generates uri for connection.
       *
       * @api private
       */

    }, {
      key: "uri",
      value: function uri() {
        var query = this.query || {};
        var schema = this.opts.secure ? "https" : "http";
        var port = ""; // cache busting is forced

        if (false !== this.opts.timestampRequests) {
          query[this.opts.timestampParam] = yeast_1();
        }

        if (!this.supportsBinary && !query.sid) {
          query.b64 = 1;
        } // avoid port if default for schema


        if (this.opts.port && ("https" === schema && Number(this.opts.port) !== 443 || "http" === schema && Number(this.opts.port) !== 80)) {
          port = ":" + this.opts.port;
        }

        var encodedQuery = parseqs.encode(query);
        var ipv6 = this.opts.hostname.indexOf(":") !== -1;
        return schema + "://" + (ipv6 ? "[" + this.opts.hostname + "]" : this.opts.hostname) + port + this.opts.path + (encodedQuery.length ? "?" + encodedQuery : "");
      }
    }]);

    return Polling;
  }(Transport);

  /**
   * Empty function
   */

  function empty() {}

  var hasXHR2 = function () {
    var xhr = new XMLHttpRequest$1({
      xdomain: false
    });
    return null != xhr.responseType;
  }();

  var XHR = /*#__PURE__*/function (_Polling) {
    _inherits(XHR, _Polling);

    var _super = _createSuper(XHR);

    /**
     * XHR Polling constructor.
     *
     * @param {Object} opts
     * @api public
     */
    function XHR(opts) {
      var _this;

      _classCallCheck(this, XHR);

      _this = _super.call(this, opts);

      if (typeof location !== "undefined") {
        var isSSL = "https:" === location.protocol;
        var port = location.port; // some user agents have empty `location.port`

        if (!port) {
          port = isSSL ? "443" : "80";
        }

        _this.xd = typeof location !== "undefined" && opts.hostname !== location.hostname || port !== opts.port;
        _this.xs = opts.secure !== isSSL;
      }
      /**
       * XHR supports binary
       */


      var forceBase64 = opts && opts.forceBase64;
      _this.supportsBinary = hasXHR2 && !forceBase64;
      return _this;
    }
    /**
     * Creates a request.
     *
     * @param {String} method
     * @api private
     */


    _createClass(XHR, [{
      key: "request",
      value: function request() {
        var opts = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};

        _extends(opts, {
          xd: this.xd,
          xs: this.xs
        }, this.opts);

        return new Request(this.uri(), opts);
      }
      /**
       * Sends data.
       *
       * @param {String} data to send.
       * @param {Function} called upon flush.
       * @api private
       */

    }, {
      key: "doWrite",
      value: function doWrite(data, fn) {
        var _this2 = this;

        var req = this.request({
          method: "POST",
          data: data
        });
        req.on("success", fn);
        req.on("error", function (err) {
          _this2.onError("xhr post error", err);
        });
      }
      /**
       * Starts a poll cycle.
       *
       * @api private
       */

    }, {
      key: "doPoll",
      value: function doPoll() {
        var _this3 = this;

        var req = this.request();
        req.on("data", this.onData.bind(this));
        req.on("error", function (err) {
          _this3.onError("xhr poll error", err);
        });
        this.pollXhr = req;
      }
    }]);

    return XHR;
  }(Polling);
  var Request = /*#__PURE__*/function (_Emitter) {
    _inherits(Request, _Emitter);

    var _super2 = _createSuper(Request);

    /**
     * Request constructor
     *
     * @param {Object} options
     * @api public
     */
    function Request(uri, opts) {
      var _this4;

      _classCallCheck(this, Request);

      _this4 = _super2.call(this);
      installTimerFunctions(_assertThisInitialized(_this4), opts);
      _this4.opts = opts;
      _this4.method = opts.method || "GET";
      _this4.uri = uri;
      _this4.async = false !== opts.async;
      _this4.data = undefined !== opts.data ? opts.data : null;

      _this4.create();

      return _this4;
    }
    /**
     * Creates the XHR object and sends the request.
     *
     * @api private
     */


    _createClass(Request, [{
      key: "create",
      value: function create() {
        var _this5 = this;

        var opts = pick(this.opts, "agent", "pfx", "key", "passphrase", "cert", "ca", "ciphers", "rejectUnauthorized", "autoUnref");
        opts.xdomain = !!this.opts.xd;
        opts.xscheme = !!this.opts.xs;
        var xhr = this.xhr = new XMLHttpRequest$1(opts);

        try {
          xhr.open(this.method, this.uri, this.async);

          try {
            if (this.opts.extraHeaders) {
              xhr.setDisableHeaderCheck && xhr.setDisableHeaderCheck(true);

              for (var i in this.opts.extraHeaders) {
                if (this.opts.extraHeaders.hasOwnProperty(i)) {
                  xhr.setRequestHeader(i, this.opts.extraHeaders[i]);
                }
              }
            }
          } catch (e) {}

          if ("POST" === this.method) {
            try {
              xhr.setRequestHeader("Content-type", "text/plain;charset=UTF-8");
            } catch (e) {}
          }

          try {
            xhr.setRequestHeader("Accept", "*/*");
          } catch (e) {} // ie6 check


          if ("withCredentials" in xhr) {
            xhr.withCredentials = this.opts.withCredentials;
          }

          if (this.opts.requestTimeout) {
            xhr.timeout = this.opts.requestTimeout;
          }

          xhr.onreadystatechange = function () {
            if (4 !== xhr.readyState) return;

            if (200 === xhr.status || 1223 === xhr.status) {
              _this5.onLoad();
            } else {
              // make sure the `error` event handler that's user-set
              // does not throw in the same tick and gets caught here
              _this5.setTimeoutFn(function () {
                _this5.onError(typeof xhr.status === "number" ? xhr.status : 0);
              }, 0);
            }
          };

          xhr.send(this.data);
        } catch (e) {
          // Need to defer since .create() is called directly from the constructor
          // and thus the 'error' event can only be only bound *after* this exception
          // occurs.  Therefore, also, we cannot throw here at all.
          this.setTimeoutFn(function () {
            _this5.onError(e);
          }, 0);
          return;
        }

        if (typeof document !== "undefined") {
          this.index = Request.requestsCount++;
          Request.requests[this.index] = this;
        }
      }
      /**
       * Called upon successful response.
       *
       * @api private
       */

    }, {
      key: "onSuccess",
      value: function onSuccess() {
        this.emit("success");
        this.cleanup();
      }
      /**
       * Called if we have data.
       *
       * @api private
       */

    }, {
      key: "onData",
      value: function onData(data) {
        this.emit("data", data);
        this.onSuccess();
      }
      /**
       * Called upon error.
       *
       * @api private
       */

    }, {
      key: "onError",
      value: function onError(err) {
        this.emit("error", err);
        this.cleanup(true);
      }
      /**
       * Cleans up house.
       *
       * @api private
       */

    }, {
      key: "cleanup",
      value: function cleanup(fromError) {
        if ("undefined" === typeof this.xhr || null === this.xhr) {
          return;
        }

        this.xhr.onreadystatechange = empty;

        if (fromError) {
          try {
            this.xhr.abort();
          } catch (e) {}
        }

        if (typeof document !== "undefined") {
          delete Request.requests[this.index];
        }

        this.xhr = null;
      }
      /**
       * Called upon load.
       *
       * @api private
       */

    }, {
      key: "onLoad",
      value: function onLoad() {
        var data = this.xhr.responseText;

        if (data !== null) {
          this.onData(data);
        }
      }
      /**
       * Aborts the request.
       *
       * @api public
       */

    }, {
      key: "abort",
      value: function abort() {
        this.cleanup();
      }
    }]);

    return Request;
  }(Emitter_1);
  Request.requestsCount = 0;
  Request.requests = {};
  /**
   * Aborts pending requests when unloading the window. This is needed to prevent
   * memory leaks (e.g. when using IE) and to ensure that no spurious error is
   * emitted.
   */

  if (typeof document !== "undefined") {
    // @ts-ignore
    if (typeof attachEvent === "function") {
      // @ts-ignore
      attachEvent("onunload", unloadHandler);
    } else if (typeof addEventListener === "function") {
      var terminationEvent = "onpagehide" in globalThis ? "pagehide" : "unload";
      addEventListener(terminationEvent, unloadHandler, false);
    }
  }

  function unloadHandler() {
    for (var i in Request.requests) {
      if (Request.requests.hasOwnProperty(i)) {
        Request.requests[i].abort();
      }
    }
  }

  var nextTick = function () {
    var isPromiseAvailable = typeof Promise === "function" && typeof Promise.resolve === "function";

    if (isPromiseAvailable) {
      return function (cb) {
        return Promise.resolve().then(cb);
      };
    } else {
      return function (cb, setTimeoutFn) {
        return setTimeoutFn(cb, 0);
      };
    }
  }();
  var WebSocket = globalThis.WebSocket || globalThis.MozWebSocket;
  var usingBrowserWebSocket = true;
  var defaultBinaryType = "arraybuffer";

  var isReactNative = typeof navigator !== "undefined" && typeof navigator.product === "string" && navigator.product.toLowerCase() === "reactnative";
  var WS = /*#__PURE__*/function (_Transport) {
    _inherits(WS, _Transport);

    var _super = _createSuper(WS);

    /**
     * WebSocket transport constructor.
     *
     * @api {Object} connection options
     * @api public
     */
    function WS(opts) {
      var _this;

      _classCallCheck(this, WS);

      _this = _super.call(this, opts);
      _this.supportsBinary = !opts.forceBase64;
      return _this;
    }
    /**
     * Transport name.
     *
     * @api public
     */


    _createClass(WS, [{
      key: "name",
      get: function get() {
        return "websocket";
      }
      /**
       * Opens socket.
       *
       * @api private
       */

    }, {
      key: "doOpen",
      value: function doOpen() {
        if (!this.check()) {
          // let probe timeout
          return;
        }

        var uri = this.uri();
        var protocols = this.opts.protocols; // React Native only supports the 'headers' option, and will print a warning if anything else is passed

        var opts = isReactNative ? {} : pick(this.opts, "agent", "perMessageDeflate", "pfx", "key", "passphrase", "cert", "ca", "ciphers", "rejectUnauthorized", "localAddress", "protocolVersion", "origin", "maxPayload", "family", "checkServerIdentity");

        if (this.opts.extraHeaders) {
          opts.headers = this.opts.extraHeaders;
        }

        try {
          this.ws = usingBrowserWebSocket && !isReactNative ? protocols ? new WebSocket(uri, protocols) : new WebSocket(uri) : new WebSocket(uri, protocols, opts);
        } catch (err) {
          return this.emit("error", err);
        }

        this.ws.binaryType = this.socket.binaryType || defaultBinaryType;
        this.addEventListeners();
      }
      /**
       * Adds event listeners to the socket
       *
       * @api private
       */

    }, {
      key: "addEventListeners",
      value: function addEventListeners() {
        var _this2 = this;

        this.ws.onopen = function () {
          if (_this2.opts.autoUnref) {
            _this2.ws._socket.unref();
          }

          _this2.onOpen();
        };

        this.ws.onclose = this.onClose.bind(this);

        this.ws.onmessage = function (ev) {
          return _this2.onData(ev.data);
        };

        this.ws.onerror = function (e) {
          return _this2.onError("websocket error", e);
        };
      }
      /**
       * Writes data to socket.
       *
       * @param {Array} array of packets.
       * @api private
       */

    }, {
      key: "write",
      value: function write(packets) {
        var _this3 = this;

        this.writable = false; // encodePacket efficient as it uses WS framing
        // no need for encodePayload

        var _loop = function _loop(i) {
          var packet = packets[i];
          var lastPacket = i === packets.length - 1;
          encodePacket(packet, _this3.supportsBinary, function (data) {
            // always create a new object (GH-437)
            var opts = {};
            // have a chance of informing us about it yet, in that case send will
            // throw an error


            try {
              if (usingBrowserWebSocket) {
                // TypeError is thrown when passing the second argument on Safari
                _this3.ws.send(data);
              }
            } catch (e) {}

            if (lastPacket) {
              // fake drain
              // defer to next tick to allow Socket to clear writeBuffer
              nextTick(function () {
                _this3.writable = true;

                _this3.emit("drain");
              }, _this3.setTimeoutFn);
            }
          });
        };

        for (var i = 0; i < packets.length; i++) {
          _loop(i);
        }
      }
      /**
       * Closes socket.
       *
       * @api private
       */

    }, {
      key: "doClose",
      value: function doClose() {
        if (typeof this.ws !== "undefined") {
          this.ws.close();
          this.ws = null;
        }
      }
      /**
       * Generates uri for connection.
       *
       * @api private
       */

    }, {
      key: "uri",
      value: function uri() {
        var query = this.query || {};
        var schema = this.opts.secure ? "wss" : "ws";
        var port = ""; // avoid port if default for schema

        if (this.opts.port && ("wss" === schema && Number(this.opts.port) !== 443 || "ws" === schema && Number(this.opts.port) !== 80)) {
          port = ":" + this.opts.port;
        } // append timestamp to URI


        if (this.opts.timestampRequests) {
          query[this.opts.timestampParam] = yeast_1();
        } // communicate binary support capabilities


        if (!this.supportsBinary) {
          query.b64 = 1;
        }

        var encodedQuery = parseqs.encode(query);
        var ipv6 = this.opts.hostname.indexOf(":") !== -1;
        return schema + "://" + (ipv6 ? "[" + this.opts.hostname + "]" : this.opts.hostname) + port + this.opts.path + (encodedQuery.length ? "?" + encodedQuery : "");
      }
      /**
       * Feature detection for WebSocket.
       *
       * @return {Boolean} whether this transport is available.
       * @api public
       */

    }, {
      key: "check",
      value: function check() {
        return !!WebSocket && !("__initialize" in WebSocket && this.name === WS.prototype.name);
      }
    }]);

    return WS;
  }(Transport);

  var transports = {
    websocket: WS,
    polling: XHR
  };

  var Socket$1 = /*#__PURE__*/function (_Emitter) {
    _inherits(Socket, _Emitter);

    var _super = _createSuper(Socket);

    /**
     * Socket constructor.
     *
     * @param {String|Object} uri or options
     * @param {Object} opts - options
     * @api public
     */
    function Socket(uri) {
      var _this;

      var opts = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};

      _classCallCheck(this, Socket);

      _this = _super.call(this);

      if (uri && "object" === _typeof(uri)) {
        opts = uri;
        uri = null;
      }

      if (uri) {
        uri = parseuri(uri);
        opts.hostname = uri.host;
        opts.secure = uri.protocol === "https" || uri.protocol === "wss";
        opts.port = uri.port;
        if (uri.query) opts.query = uri.query;
      } else if (opts.host) {
        opts.hostname = parseuri(opts.host).host;
      }

      installTimerFunctions(_assertThisInitialized(_this), opts);
      _this.secure = null != opts.secure ? opts.secure : typeof location !== "undefined" && "https:" === location.protocol;

      if (opts.hostname && !opts.port) {
        // if no port is specified manually, use the protocol default
        opts.port = _this.secure ? "443" : "80";
      }

      _this.hostname = opts.hostname || (typeof location !== "undefined" ? location.hostname : "localhost");
      _this.port = opts.port || (typeof location !== "undefined" && location.port ? location.port : _this.secure ? "443" : "80");
      _this.transports = opts.transports || ["polling", "websocket"];
      _this.readyState = "";
      _this.writeBuffer = [];
      _this.prevBufferLen = 0;
      _this.opts = _extends({
        path: "/engine.io",
        agent: false,
        withCredentials: false,
        upgrade: true,
        timestampParam: "t",
        rememberUpgrade: false,
        rejectUnauthorized: true,
        perMessageDeflate: {
          threshold: 1024
        },
        transportOptions: {},
        closeOnBeforeunload: true
      }, opts);
      _this.opts.path = _this.opts.path.replace(/\/$/, "") + "/";

      if (typeof _this.opts.query === "string") {
        _this.opts.query = parseqs.decode(_this.opts.query);
      } // set on handshake


      _this.id = null;
      _this.upgrades = null;
      _this.pingInterval = null;
      _this.pingTimeout = null; // set on heartbeat

      _this.pingTimeoutTimer = null;

      if (typeof addEventListener === "function") {
        if (_this.opts.closeOnBeforeunload) {
          // Firefox closes the connection when the "beforeunload" event is emitted but not Chrome. This event listener
          // ensures every browser behaves the same (no "disconnect" event at the Socket.IO level when the page is
          // closed/reloaded)
          addEventListener("beforeunload", function () {
            if (_this.transport) {
              // silently close the transport
              _this.transport.removeAllListeners();

              _this.transport.close();
            }
          }, false);
        }

        if (_this.hostname !== "localhost") {
          _this.offlineEventListener = function () {
            _this.onClose("transport close");
          };

          addEventListener("offline", _this.offlineEventListener, false);
        }
      }

      _this.open();

      return _this;
    }
    /**
     * Creates transport of the given type.
     *
     * @param {String} transport name
     * @return {Transport}
     * @api private
     */


    _createClass(Socket, [{
      key: "createTransport",
      value: function createTransport(name) {
        var query = clone(this.opts.query); // append engine.io protocol identifier

        query.EIO = protocol$1; // transport name

        query.transport = name; // session id if we already have one

        if (this.id) query.sid = this.id;

        var opts = _extends({}, this.opts.transportOptions[name], this.opts, {
          query: query,
          socket: this,
          hostname: this.hostname,
          secure: this.secure,
          port: this.port
        });

        return new transports[name](opts);
      }
      /**
       * Initializes transport to use and starts probe.
       *
       * @api private
       */

    }, {
      key: "open",
      value: function open() {
        var _this2 = this;

        var transport;

        if (this.opts.rememberUpgrade && Socket.priorWebsocketSuccess && this.transports.indexOf("websocket") !== -1) {
          transport = "websocket";
        } else if (0 === this.transports.length) {
          // Emit error on next tick so it can be listened to
          this.setTimeoutFn(function () {
            _this2.emitReserved("error", "No transports available");
          }, 0);
          return;
        } else {
          transport = this.transports[0];
        }

        this.readyState = "opening"; // Retry with the next transport if the transport is disabled (jsonp: false)

        try {
          transport = this.createTransport(transport);
        } catch (e) {
          this.transports.shift();
          this.open();
          return;
        }

        transport.open();
        this.setTransport(transport);
      }
      /**
       * Sets the current transport. Disables the existing one (if any).
       *
       * @api private
       */

    }, {
      key: "setTransport",
      value: function setTransport(transport) {
        var _this3 = this;

        if (this.transport) {
          this.transport.removeAllListeners();
        } // set up transport


        this.transport = transport; // set up transport listeners

        transport.on("drain", this.onDrain.bind(this)).on("packet", this.onPacket.bind(this)).on("error", this.onError.bind(this)).on("close", function () {
          _this3.onClose("transport close");
        });
      }
      /**
       * Probes a transport.
       *
       * @param {String} transport name
       * @api private
       */

    }, {
      key: "probe",
      value: function probe(name) {
        var _this4 = this;

        var transport = this.createTransport(name);
        var failed = false;
        Socket.priorWebsocketSuccess = false;

        var onTransportOpen = function onTransportOpen() {
          if (failed) return;
          transport.send([{
            type: "ping",
            data: "probe"
          }]);
          transport.once("packet", function (msg) {
            if (failed) return;

            if ("pong" === msg.type && "probe" === msg.data) {
              _this4.upgrading = true;

              _this4.emitReserved("upgrading", transport);

              if (!transport) return;
              Socket.priorWebsocketSuccess = "websocket" === transport.name;

              _this4.transport.pause(function () {
                if (failed) return;
                if ("closed" === _this4.readyState) return;
                cleanup();

                _this4.setTransport(transport);

                transport.send([{
                  type: "upgrade"
                }]);

                _this4.emitReserved("upgrade", transport);

                transport = null;
                _this4.upgrading = false;

                _this4.flush();
              });
            } else {
              var err = new Error("probe error"); // @ts-ignore

              err.transport = transport.name;

              _this4.emitReserved("upgradeError", err);
            }
          });
        };

        function freezeTransport() {
          if (failed) return; // Any callback called by transport should be ignored since now

          failed = true;
          cleanup();
          transport.close();
          transport = null;
        } // Handle any error that happens while probing


        var onerror = function onerror(err) {
          var error = new Error("probe error: " + err); // @ts-ignore

          error.transport = transport.name;
          freezeTransport();

          _this4.emitReserved("upgradeError", error);
        };

        function onTransportClose() {
          onerror("transport closed");
        } // When the socket is closed while we're probing


        function onclose() {
          onerror("socket closed");
        } // When the socket is upgraded while we're probing


        function onupgrade(to) {
          if (transport && to.name !== transport.name) {
            freezeTransport();
          }
        } // Remove all listeners on the transport and on self


        var cleanup = function cleanup() {
          transport.removeListener("open", onTransportOpen);
          transport.removeListener("error", onerror);
          transport.removeListener("close", onTransportClose);

          _this4.off("close", onclose);

          _this4.off("upgrading", onupgrade);
        };

        transport.once("open", onTransportOpen);
        transport.once("error", onerror);
        transport.once("close", onTransportClose);
        this.once("close", onclose);
        this.once("upgrading", onupgrade);
        transport.open();
      }
      /**
       * Called when connection is deemed open.
       *
       * @api private
       */

    }, {
      key: "onOpen",
      value: function onOpen() {
        this.readyState = "open";
        Socket.priorWebsocketSuccess = "websocket" === this.transport.name;
        this.emitReserved("open");
        this.flush(); // we check for `readyState` in case an `open`
        // listener already closed the socket

        if ("open" === this.readyState && this.opts.upgrade && this.transport.pause) {
          var i = 0;
          var l = this.upgrades.length;

          for (; i < l; i++) {
            this.probe(this.upgrades[i]);
          }
        }
      }
      /**
       * Handles a packet.
       *
       * @api private
       */

    }, {
      key: "onPacket",
      value: function onPacket(packet) {
        if ("opening" === this.readyState || "open" === this.readyState || "closing" === this.readyState) {
          this.emitReserved("packet", packet); // Socket is live - any packet counts

          this.emitReserved("heartbeat");

          switch (packet.type) {
            case "open":
              this.onHandshake(JSON.parse(packet.data));
              break;

            case "ping":
              this.resetPingTimeout();
              this.sendPacket("pong");
              this.emitReserved("ping");
              this.emitReserved("pong");
              break;

            case "error":
              var err = new Error("server error"); // @ts-ignore

              err.code = packet.data;
              this.onError(err);
              break;

            case "message":
              this.emitReserved("data", packet.data);
              this.emitReserved("message", packet.data);
              break;
          }
        }
      }
      /**
       * Called upon handshake completion.
       *
       * @param {Object} data - handshake obj
       * @api private
       */

    }, {
      key: "onHandshake",
      value: function onHandshake(data) {
        this.emitReserved("handshake", data);
        this.id = data.sid;
        this.transport.query.sid = data.sid;
        this.upgrades = this.filterUpgrades(data.upgrades);
        this.pingInterval = data.pingInterval;
        this.pingTimeout = data.pingTimeout;
        this.onOpen(); // In case open handler closes socket

        if ("closed" === this.readyState) return;
        this.resetPingTimeout();
      }
      /**
       * Sets and resets ping timeout timer based on server pings.
       *
       * @api private
       */

    }, {
      key: "resetPingTimeout",
      value: function resetPingTimeout() {
        var _this5 = this;

        this.clearTimeoutFn(this.pingTimeoutTimer);
        this.pingTimeoutTimer = this.setTimeoutFn(function () {
          _this5.onClose("ping timeout");
        }, this.pingInterval + this.pingTimeout);

        if (this.opts.autoUnref) {
          this.pingTimeoutTimer.unref();
        }
      }
      /**
       * Called on `drain` event
       *
       * @api private
       */

    }, {
      key: "onDrain",
      value: function onDrain() {
        this.writeBuffer.splice(0, this.prevBufferLen); // setting prevBufferLen = 0 is very important
        // for example, when upgrading, upgrade packet is sent over,
        // and a nonzero prevBufferLen could cause problems on `drain`

        this.prevBufferLen = 0;

        if (0 === this.writeBuffer.length) {
          this.emitReserved("drain");
        } else {
          this.flush();
        }
      }
      /**
       * Flush write buffers.
       *
       * @api private
       */

    }, {
      key: "flush",
      value: function flush() {
        if ("closed" !== this.readyState && this.transport.writable && !this.upgrading && this.writeBuffer.length) {
          this.transport.send(this.writeBuffer); // keep track of current length of writeBuffer
          // splice writeBuffer and callbackBuffer on `drain`

          this.prevBufferLen = this.writeBuffer.length;
          this.emitReserved("flush");
        }
      }
      /**
       * Sends a message.
       *
       * @param {String} message.
       * @param {Function} callback function.
       * @param {Object} options.
       * @return {Socket} for chaining.
       * @api public
       */

    }, {
      key: "write",
      value: function write(msg, options, fn) {
        this.sendPacket("message", msg, options, fn);
        return this;
      }
    }, {
      key: "send",
      value: function send(msg, options, fn) {
        this.sendPacket("message", msg, options, fn);
        return this;
      }
      /**
       * Sends a packet.
       *
       * @param {String} packet type.
       * @param {String} data.
       * @param {Object} options.
       * @param {Function} callback function.
       * @api private
       */

    }, {
      key: "sendPacket",
      value: function sendPacket(type, data, options, fn) {
        if ("function" === typeof data) {
          fn = data;
          data = undefined;
        }

        if ("function" === typeof options) {
          fn = options;
          options = null;
        }

        if ("closing" === this.readyState || "closed" === this.readyState) {
          return;
        }

        options = options || {};
        options.compress = false !== options.compress;
        var packet = {
          type: type,
          data: data,
          options: options
        };
        this.emitReserved("packetCreate", packet);
        this.writeBuffer.push(packet);
        if (fn) this.once("flush", fn);
        this.flush();
      }
      /**
       * Closes the connection.
       *
       * @api public
       */

    }, {
      key: "close",
      value: function close() {
        var _this6 = this;

        var close = function close() {
          _this6.onClose("forced close");

          _this6.transport.close();
        };

        var cleanupAndClose = function cleanupAndClose() {
          _this6.off("upgrade", cleanupAndClose);

          _this6.off("upgradeError", cleanupAndClose);

          close();
        };

        var waitForUpgrade = function waitForUpgrade() {
          // wait for upgrade to finish since we can't send packets while pausing a transport
          _this6.once("upgrade", cleanupAndClose);

          _this6.once("upgradeError", cleanupAndClose);
        };

        if ("opening" === this.readyState || "open" === this.readyState) {
          this.readyState = "closing";

          if (this.writeBuffer.length) {
            this.once("drain", function () {
              if (_this6.upgrading) {
                waitForUpgrade();
              } else {
                close();
              }
            });
          } else if (this.upgrading) {
            waitForUpgrade();
          } else {
            close();
          }
        }

        return this;
      }
      /**
       * Called upon transport error
       *
       * @api private
       */

    }, {
      key: "onError",
      value: function onError(err) {
        Socket.priorWebsocketSuccess = false;
        this.emitReserved("error", err);
        this.onClose("transport error", err);
      }
      /**
       * Called upon transport close.
       *
       * @api private
       */

    }, {
      key: "onClose",
      value: function onClose(reason, desc) {
        if ("opening" === this.readyState || "open" === this.readyState || "closing" === this.readyState) {
          // clear timers
          this.clearTimeoutFn(this.pingTimeoutTimer); // stop event from firing again for transport

          this.transport.removeAllListeners("close"); // ensure transport won't stay open

          this.transport.close(); // ignore further transport communication

          this.transport.removeAllListeners();

          if (typeof removeEventListener === "function") {
            removeEventListener("offline", this.offlineEventListener, false);
          } // set ready state


          this.readyState = "closed"; // clear session id

          this.id = null; // emit close event

          this.emitReserved("close", reason, desc); // clean buffers after, so users can still
          // grab the buffers on `close` event

          this.writeBuffer = [];
          this.prevBufferLen = 0;
        }
      }
      /**
       * Filters upgrades, returning only those matching client transports.
       *
       * @param {Array} server upgrades
       * @api private
       *
       */

    }, {
      key: "filterUpgrades",
      value: function filterUpgrades(upgrades) {
        var filteredUpgrades = [];
        var i = 0;
        var j = upgrades.length;

        for (; i < j; i++) {
          if (~this.transports.indexOf(upgrades[i])) filteredUpgrades.push(upgrades[i]);
        }

        return filteredUpgrades;
      }
    }]);

    return Socket;
  }(Emitter_1);
  Socket$1.protocol = protocol$1;

  function clone(obj) {
    var o = {};

    for (var i in obj) {
      if (obj.hasOwnProperty(i)) {
        o[i] = obj[i];
      }
    }

    return o;
  }

  var withNativeArrayBuffer = typeof ArrayBuffer === "function";

  var isView = function isView(obj) {
    return typeof ArrayBuffer.isView === "function" ? ArrayBuffer.isView(obj) : obj.buffer instanceof ArrayBuffer;
  };

  var toString = Object.prototype.toString;
  var withNativeBlob = typeof Blob === "function" || typeof Blob !== "undefined" && toString.call(Blob) === "[object BlobConstructor]";
  var withNativeFile = typeof File === "function" || typeof File !== "undefined" && toString.call(File) === "[object FileConstructor]";
  /**
   * Returns true if obj is a Buffer, an ArrayBuffer, a Blob or a File.
   *
   * @private
   */

  function isBinary(obj) {
    return withNativeArrayBuffer && (obj instanceof ArrayBuffer || isView(obj)) || withNativeBlob && obj instanceof Blob || withNativeFile && obj instanceof File;
  }
  function hasBinary(obj, toJSON) {
    if (!obj || _typeof(obj) !== "object") {
      return false;
    }

    if (Array.isArray(obj)) {
      for (var i = 0, l = obj.length; i < l; i++) {
        if (hasBinary(obj[i])) {
          return true;
        }
      }

      return false;
    }

    if (isBinary(obj)) {
      return true;
    }

    if (obj.toJSON && typeof obj.toJSON === "function" && arguments.length === 1) {
      return hasBinary(obj.toJSON(), true);
    }

    for (var key in obj) {
      if (Object.prototype.hasOwnProperty.call(obj, key) && hasBinary(obj[key])) {
        return true;
      }
    }

    return false;
  }

  /**
   * Replaces every Buffer | ArrayBuffer | Blob | File in packet with a numbered placeholder.
   *
   * @param {Object} packet - socket.io event packet
   * @return {Object} with deconstructed packet and list of buffers
   * @public
   */

  function deconstructPacket(packet) {
    var buffers = [];
    var packetData = packet.data;
    var pack = packet;
    pack.data = _deconstructPacket(packetData, buffers);
    pack.attachments = buffers.length; // number of binary 'attachments'

    return {
      packet: pack,
      buffers: buffers
    };
  }

  function _deconstructPacket(data, buffers) {
    if (!data) return data;

    if (isBinary(data)) {
      var placeholder = {
        _placeholder: true,
        num: buffers.length
      };
      buffers.push(data);
      return placeholder;
    } else if (Array.isArray(data)) {
      var newData = new Array(data.length);

      for (var i = 0; i < data.length; i++) {
        newData[i] = _deconstructPacket(data[i], buffers);
      }

      return newData;
    } else if (_typeof(data) === "object" && !(data instanceof Date)) {
      var _newData = {};

      for (var key in data) {
        if (data.hasOwnProperty(key)) {
          _newData[key] = _deconstructPacket(data[key], buffers);
        }
      }

      return _newData;
    }

    return data;
  }
  /**
   * Reconstructs a binary packet from its placeholder packet and buffers
   *
   * @param {Object} packet - event packet with placeholders
   * @param {Array} buffers - binary buffers to put in placeholder positions
   * @return {Object} reconstructed packet
   * @public
   */


  function reconstructPacket(packet, buffers) {
    packet.data = _reconstructPacket(packet.data, buffers);
    packet.attachments = undefined; // no longer useful

    return packet;
  }

  function _reconstructPacket(data, buffers) {
    if (!data) return data;

    if (data && data._placeholder) {
      return buffers[data.num]; // appropriate buffer (should be natural order anyway)
    } else if (Array.isArray(data)) {
      for (var i = 0; i < data.length; i++) {
        data[i] = _reconstructPacket(data[i], buffers);
      }
    } else if (_typeof(data) === "object") {
      for (var key in data) {
        if (data.hasOwnProperty(key)) {
          data[key] = _reconstructPacket(data[key], buffers);
        }
      }
    }

    return data;
  }

  /**
   * Protocol version.
   *
   * @public
   */

  var protocol = 5;
  var PacketType;

  (function (PacketType) {
    PacketType[PacketType["CONNECT"] = 0] = "CONNECT";
    PacketType[PacketType["DISCONNECT"] = 1] = "DISCONNECT";
    PacketType[PacketType["EVENT"] = 2] = "EVENT";
    PacketType[PacketType["ACK"] = 3] = "ACK";
    PacketType[PacketType["CONNECT_ERROR"] = 4] = "CONNECT_ERROR";
    PacketType[PacketType["BINARY_EVENT"] = 5] = "BINARY_EVENT";
    PacketType[PacketType["BINARY_ACK"] = 6] = "BINARY_ACK";
  })(PacketType || (PacketType = {}));
  /**
   * A socket.io Encoder instance
   */


  var Encoder = /*#__PURE__*/function () {
    function Encoder() {
      _classCallCheck(this, Encoder);
    }

    _createClass(Encoder, [{
      key: "encode",
      value:
      /**
       * Encode a packet as a single string if non-binary, or as a
       * buffer sequence, depending on packet type.
       *
       * @param {Object} obj - packet object
       */
      function encode(obj) {
        if (obj.type === PacketType.EVENT || obj.type === PacketType.ACK) {
          if (hasBinary(obj)) {
            obj.type = obj.type === PacketType.EVENT ? PacketType.BINARY_EVENT : PacketType.BINARY_ACK;
            return this.encodeAsBinary(obj);
          }
        }

        return [this.encodeAsString(obj)];
      }
      /**
       * Encode packet as string.
       */

    }, {
      key: "encodeAsString",
      value: function encodeAsString(obj) {
        // first is type
        var str = "" + obj.type; // attachments if we have them

        if (obj.type === PacketType.BINARY_EVENT || obj.type === PacketType.BINARY_ACK) {
          str += obj.attachments + "-";
        } // if we have a namespace other than `/`
        // we append it followed by a comma `,`


        if (obj.nsp && "/" !== obj.nsp) {
          str += obj.nsp + ",";
        } // immediately followed by the id


        if (null != obj.id) {
          str += obj.id;
        } // json data


        if (null != obj.data) {
          str += JSON.stringify(obj.data);
        }

        return str;
      }
      /**
       * Encode packet as 'buffer sequence' by removing blobs, and
       * deconstructing packet into object with placeholders and
       * a list of buffers.
       */

    }, {
      key: "encodeAsBinary",
      value: function encodeAsBinary(obj) {
        var deconstruction = deconstructPacket(obj);
        var pack = this.encodeAsString(deconstruction.packet);
        var buffers = deconstruction.buffers;
        buffers.unshift(pack); // add packet info to beginning of data list

        return buffers; // write all the buffers
      }
    }]);

    return Encoder;
  }();
  /**
   * A socket.io Decoder instance
   *
   * @return {Object} decoder
   */

  var Decoder = /*#__PURE__*/function (_Emitter) {
    _inherits(Decoder, _Emitter);

    var _super = _createSuper(Decoder);

    function Decoder() {
      _classCallCheck(this, Decoder);

      return _super.call(this);
    }
    /**
     * Decodes an encoded packet string into packet JSON.
     *
     * @param {String} obj - encoded packet
     */


    _createClass(Decoder, [{
      key: "add",
      value: function add(obj) {
        var packet;

        if (typeof obj === "string") {
          packet = this.decodeString(obj);

          if (packet.type === PacketType.BINARY_EVENT || packet.type === PacketType.BINARY_ACK) {
            // binary packet's json
            this.reconstructor = new BinaryReconstructor(packet); // no attachments, labeled binary but no binary data to follow

            if (packet.attachments === 0) {
              _get(_getPrototypeOf(Decoder.prototype), "emitReserved", this).call(this, "decoded", packet);
            }
          } else {
            // non-binary full packet
            _get(_getPrototypeOf(Decoder.prototype), "emitReserved", this).call(this, "decoded", packet);
          }
        } else if (isBinary(obj) || obj.base64) {
          // raw binary data
          if (!this.reconstructor) {
            throw new Error("got binary data when not reconstructing a packet");
          } else {
            packet = this.reconstructor.takeBinaryData(obj);

            if (packet) {
              // received final buffer
              this.reconstructor = null;

              _get(_getPrototypeOf(Decoder.prototype), "emitReserved", this).call(this, "decoded", packet);
            }
          }
        } else {
          throw new Error("Unknown type: " + obj);
        }
      }
      /**
       * Decode a packet String (JSON data)
       *
       * @param {String} str
       * @return {Object} packet
       */

    }, {
      key: "decodeString",
      value: function decodeString(str) {
        var i = 0; // look up type

        var p = {
          type: Number(str.charAt(0))
        };

        if (PacketType[p.type] === undefined) {
          throw new Error("unknown packet type " + p.type);
        } // look up attachments if type binary


        if (p.type === PacketType.BINARY_EVENT || p.type === PacketType.BINARY_ACK) {
          var start = i + 1;

          while (str.charAt(++i) !== "-" && i != str.length) {}

          var buf = str.substring(start, i);

          if (buf != Number(buf) || str.charAt(i) !== "-") {
            throw new Error("Illegal attachments");
          }

          p.attachments = Number(buf);
        } // look up namespace (if any)


        if ("/" === str.charAt(i + 1)) {
          var _start = i + 1;

          while (++i) {
            var c = str.charAt(i);
            if ("," === c) break;
            if (i === str.length) break;
          }

          p.nsp = str.substring(_start, i);
        } else {
          p.nsp = "/";
        } // look up id


        var next = str.charAt(i + 1);

        if ("" !== next && Number(next) == next) {
          var _start2 = i + 1;

          while (++i) {
            var _c = str.charAt(i);

            if (null == _c || Number(_c) != _c) {
              --i;
              break;
            }

            if (i === str.length) break;
          }

          p.id = Number(str.substring(_start2, i + 1));
        } // look up json data


        if (str.charAt(++i)) {
          var payload = tryParse(str.substr(i));

          if (Decoder.isPayloadValid(p.type, payload)) {
            p.data = payload;
          } else {
            throw new Error("invalid payload");
          }
        }

        return p;
      }
    }, {
      key: "destroy",
      value:
      /**
       * Deallocates a parser's resources
       */
      function destroy() {
        if (this.reconstructor) {
          this.reconstructor.finishedReconstruction();
        }
      }
    }], [{
      key: "isPayloadValid",
      value: function isPayloadValid(type, payload) {
        switch (type) {
          case PacketType.CONNECT:
            return _typeof(payload) === "object";

          case PacketType.DISCONNECT:
            return payload === undefined;

          case PacketType.CONNECT_ERROR:
            return typeof payload === "string" || _typeof(payload) === "object";

          case PacketType.EVENT:
          case PacketType.BINARY_EVENT:
            return Array.isArray(payload) && payload.length > 0;

          case PacketType.ACK:
          case PacketType.BINARY_ACK:
            return Array.isArray(payload);
        }
      }
    }]);

    return Decoder;
  }(Emitter_1);

  function tryParse(str) {
    try {
      return JSON.parse(str);
    } catch (e) {
      return false;
    }
  }
  /**
   * A manager of a binary event's 'buffer sequence'. Should
   * be constructed whenever a packet of type BINARY_EVENT is
   * decoded.
   *
   * @param {Object} packet
   * @return {BinaryReconstructor} initialized reconstructor
   */


  var BinaryReconstructor = /*#__PURE__*/function () {
    function BinaryReconstructor(packet) {
      _classCallCheck(this, BinaryReconstructor);

      this.packet = packet;
      this.buffers = [];
      this.reconPack = packet;
    }
    /**
     * Method to be called when binary data received from connection
     * after a BINARY_EVENT packet.
     *
     * @param {Buffer | ArrayBuffer} binData - the raw binary data received
     * @return {null | Object} returns null if more binary data is expected or
     *   a reconstructed packet object if all buffers have been received.
     */


    _createClass(BinaryReconstructor, [{
      key: "takeBinaryData",
      value: function takeBinaryData(binData) {
        this.buffers.push(binData);

        if (this.buffers.length === this.reconPack.attachments) {
          // done with buffer list
          var packet = reconstructPacket(this.reconPack, this.buffers);
          this.finishedReconstruction();
          return packet;
        }

        return null;
      }
      /**
       * Cleans up binary packet reconstruction variables.
       */

    }, {
      key: "finishedReconstruction",
      value: function finishedReconstruction() {
        this.reconPack = null;
        this.buffers = [];
      }
    }]);

    return BinaryReconstructor;
  }();

  var parser = /*#__PURE__*/Object.freeze({
    __proto__: null,
    protocol: protocol,
    get PacketType () { return PacketType; },
    Encoder: Encoder,
    Decoder: Decoder
  });

  function on(obj, ev, fn) {
    obj.on(ev, fn);
    return function subDestroy() {
      obj.off(ev, fn);
    };
  }

  /**
   * Internal events.
   * These events can't be emitted by the user.
   */

  var RESERVED_EVENTS = Object.freeze({
    connect: 1,
    connect_error: 1,
    disconnect: 1,
    disconnecting: 1,
    // EventEmitter reserved events: https://nodejs.org/api/events.html#events_event_newlistener
    newListener: 1,
    removeListener: 1
  });
  var Socket = /*#__PURE__*/function (_Emitter) {
    _inherits(Socket, _Emitter);

    var _super = _createSuper(Socket);

    /**
     * `Socket` constructor.
     *
     * @public
     */
    function Socket(io, nsp, opts) {
      var _this;

      _classCallCheck(this, Socket);

      _this = _super.call(this);
      _this.connected = false;
      _this.disconnected = true;
      _this.receiveBuffer = [];
      _this.sendBuffer = [];
      _this.ids = 0;
      _this.acks = {};
      _this.flags = {};
      _this.io = io;
      _this.nsp = nsp;

      if (opts && opts.auth) {
        _this.auth = opts.auth;
      }

      if (_this.io._autoConnect) _this.open();
      return _this;
    }
    /**
     * Subscribe to open, close and packet events
     *
     * @private
     */


    _createClass(Socket, [{
      key: "subEvents",
      value: function subEvents() {
        if (this.subs) return;
        var io = this.io;
        this.subs = [on(io, "open", this.onopen.bind(this)), on(io, "packet", this.onpacket.bind(this)), on(io, "error", this.onerror.bind(this)), on(io, "close", this.onclose.bind(this))];
      }
      /**
       * Whether the Socket will try to reconnect when its Manager connects or reconnects
       */

    }, {
      key: "active",
      get: function get() {
        return !!this.subs;
      }
      /**
       * "Opens" the socket.
       *
       * @public
       */

    }, {
      key: "connect",
      value: function connect() {
        if (this.connected) return this;
        this.subEvents();
        if (!this.io["_reconnecting"]) this.io.open(); // ensure open

        if ("open" === this.io._readyState) this.onopen();
        return this;
      }
      /**
       * Alias for connect()
       */

    }, {
      key: "open",
      value: function open() {
        return this.connect();
      }
      /**
       * Sends a `message` event.
       *
       * @return self
       * @public
       */

    }, {
      key: "send",
      value: function send() {
        for (var _len = arguments.length, args = new Array(_len), _key = 0; _key < _len; _key++) {
          args[_key] = arguments[_key];
        }

        args.unshift("message");
        this.emit.apply(this, args);
        return this;
      }
      /**
       * Override `emit`.
       * If the event is in `events`, it's emitted normally.
       *
       * @return self
       * @public
       */

    }, {
      key: "emit",
      value: function emit(ev) {
        if (RESERVED_EVENTS.hasOwnProperty(ev)) {
          throw new Error('"' + ev + '" is a reserved event name');
        }

        for (var _len2 = arguments.length, args = new Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
          args[_key2 - 1] = arguments[_key2];
        }

        args.unshift(ev);
        var packet = {
          type: PacketType.EVENT,
          data: args
        };
        packet.options = {};
        packet.options.compress = this.flags.compress !== false; // event ack callback

        if ("function" === typeof args[args.length - 1]) {
          var id = this.ids++;
          var ack = args.pop();

          this._registerAckCallback(id, ack);

          packet.id = id;
        }

        var isTransportWritable = this.io.engine && this.io.engine.transport && this.io.engine.transport.writable;
        var discardPacket = this.flags["volatile"] && (!isTransportWritable || !this.connected);

        if (discardPacket) ; else if (this.connected) {
          this.packet(packet);
        } else {
          this.sendBuffer.push(packet);
        }

        this.flags = {};
        return this;
      }
      /**
       * @private
       */

    }, {
      key: "_registerAckCallback",
      value: function _registerAckCallback(id, ack) {
        var _this2 = this;

        var timeout = this.flags.timeout;

        if (timeout === undefined) {
          this.acks[id] = ack;
          return;
        } // @ts-ignore


        var timer = this.io.setTimeoutFn(function () {
          delete _this2.acks[id];

          for (var i = 0; i < _this2.sendBuffer.length; i++) {
            if (_this2.sendBuffer[i].id === id) {
              _this2.sendBuffer.splice(i, 1);
            }
          }

          ack.call(_this2, new Error("operation has timed out"));
        }, timeout);

        this.acks[id] = function () {
          // @ts-ignore
          _this2.io.clearTimeoutFn(timer);

          for (var _len3 = arguments.length, args = new Array(_len3), _key3 = 0; _key3 < _len3; _key3++) {
            args[_key3] = arguments[_key3];
          }

          ack.apply(_this2, [null].concat(args));
        };
      }
      /**
       * Sends a packet.
       *
       * @param packet
       * @private
       */

    }, {
      key: "packet",
      value: function packet(_packet) {
        _packet.nsp = this.nsp;

        this.io._packet(_packet);
      }
      /**
       * Called upon engine `open`.
       *
       * @private
       */

    }, {
      key: "onopen",
      value: function onopen() {
        var _this3 = this;

        if (typeof this.auth == "function") {
          this.auth(function (data) {
            _this3.packet({
              type: PacketType.CONNECT,
              data: data
            });
          });
        } else {
          this.packet({
            type: PacketType.CONNECT,
            data: this.auth
          });
        }
      }
      /**
       * Called upon engine or manager `error`.
       *
       * @param err
       * @private
       */

    }, {
      key: "onerror",
      value: function onerror(err) {
        if (!this.connected) {
          this.emitReserved("connect_error", err);
        }
      }
      /**
       * Called upon engine `close`.
       *
       * @param reason
       * @private
       */

    }, {
      key: "onclose",
      value: function onclose(reason) {
        this.connected = false;
        this.disconnected = true;
        delete this.id;
        this.emitReserved("disconnect", reason);
      }
      /**
       * Called with socket packet.
       *
       * @param packet
       * @private
       */

    }, {
      key: "onpacket",
      value: function onpacket(packet) {
        var sameNamespace = packet.nsp === this.nsp;
        if (!sameNamespace) return;

        switch (packet.type) {
          case PacketType.CONNECT:
            if (packet.data && packet.data.sid) {
              var id = packet.data.sid;
              this.onconnect(id);
            } else {
              this.emitReserved("connect_error", new Error("It seems you are trying to reach a Socket.IO server in v2.x with a v3.x client, but they are not compatible (more information here: https://socket.io/docs/v3/migrating-from-2-x-to-3-0/)"));
            }

            break;

          case PacketType.EVENT:
            this.onevent(packet);
            break;

          case PacketType.BINARY_EVENT:
            this.onevent(packet);
            break;

          case PacketType.ACK:
            this.onack(packet);
            break;

          case PacketType.BINARY_ACK:
            this.onack(packet);
            break;

          case PacketType.DISCONNECT:
            this.ondisconnect();
            break;

          case PacketType.CONNECT_ERROR:
            this.destroy();
            var err = new Error(packet.data.message); // @ts-ignore

            err.data = packet.data.data;
            this.emitReserved("connect_error", err);
            break;
        }
      }
      /**
       * Called upon a server event.
       *
       * @param packet
       * @private
       */

    }, {
      key: "onevent",
      value: function onevent(packet) {
        var args = packet.data || [];

        if (null != packet.id) {
          args.push(this.ack(packet.id));
        }

        if (this.connected) {
          this.emitEvent(args);
        } else {
          this.receiveBuffer.push(Object.freeze(args));
        }
      }
    }, {
      key: "emitEvent",
      value: function emitEvent(args) {
        if (this._anyListeners && this._anyListeners.length) {
          var listeners = this._anyListeners.slice();

          var _iterator = _createForOfIteratorHelper(listeners),
              _step;

          try {
            for (_iterator.s(); !(_step = _iterator.n()).done;) {
              var listener = _step.value;
              listener.apply(this, args);
            }
          } catch (err) {
            _iterator.e(err);
          } finally {
            _iterator.f();
          }
        }

        _get(_getPrototypeOf(Socket.prototype), "emit", this).apply(this, args);
      }
      /**
       * Produces an ack callback to emit with an event.
       *
       * @private
       */

    }, {
      key: "ack",
      value: function ack(id) {
        var self = this;
        var sent = false;
        return function () {
          // prevent double callbacks
          if (sent) return;
          sent = true;

          for (var _len4 = arguments.length, args = new Array(_len4), _key4 = 0; _key4 < _len4; _key4++) {
            args[_key4] = arguments[_key4];
          }

          self.packet({
            type: PacketType.ACK,
            id: id,
            data: args
          });
        };
      }
      /**
       * Called upon a server acknowlegement.
       *
       * @param packet
       * @private
       */

    }, {
      key: "onack",
      value: function onack(packet) {
        var ack = this.acks[packet.id];

        if ("function" === typeof ack) {
          ack.apply(this, packet.data);
          delete this.acks[packet.id];
        }
      }
      /**
       * Called upon server connect.
       *
       * @private
       */

    }, {
      key: "onconnect",
      value: function onconnect(id) {
        this.id = id;
        this.connected = true;
        this.disconnected = false;
        this.emitBuffered();
        this.emitReserved("connect");
      }
      /**
       * Emit buffered events (received and emitted).
       *
       * @private
       */

    }, {
      key: "emitBuffered",
      value: function emitBuffered() {
        var _this4 = this;

        this.receiveBuffer.forEach(function (args) {
          return _this4.emitEvent(args);
        });
        this.receiveBuffer = [];
        this.sendBuffer.forEach(function (packet) {
          return _this4.packet(packet);
        });
        this.sendBuffer = [];
      }
      /**
       * Called upon server disconnect.
       *
       * @private
       */

    }, {
      key: "ondisconnect",
      value: function ondisconnect() {
        this.destroy();
        this.onclose("io server disconnect");
      }
      /**
       * Called upon forced client/server side disconnections,
       * this method ensures the manager stops tracking us and
       * that reconnections don't get triggered for this.
       *
       * @private
       */

    }, {
      key: "destroy",
      value: function destroy() {
        if (this.subs) {
          // clean subscriptions to avoid reconnections
          this.subs.forEach(function (subDestroy) {
            return subDestroy();
          });
          this.subs = undefined;
        }

        this.io["_destroy"](this);
      }
      /**
       * Disconnects the socket manually.
       *
       * @return self
       * @public
       */

    }, {
      key: "disconnect",
      value: function disconnect() {
        if (this.connected) {
          this.packet({
            type: PacketType.DISCONNECT
          });
        } // remove socket from pool


        this.destroy();

        if (this.connected) {
          // fire events
          this.onclose("io client disconnect");
        }

        return this;
      }
      /**
       * Alias for disconnect()
       *
       * @return self
       * @public
       */

    }, {
      key: "close",
      value: function close() {
        return this.disconnect();
      }
      /**
       * Sets the compress flag.
       *
       * @param compress - if `true`, compresses the sending data
       * @return self
       * @public
       */

    }, {
      key: "compress",
      value: function compress(_compress) {
        this.flags.compress = _compress;
        return this;
      }
      /**
       * Sets a modifier for a subsequent event emission that the event message will be dropped when this socket is not
       * ready to send messages.
       *
       * @returns self
       * @public
       */

    }, {
      key: "volatile",
      get: function get() {
        this.flags["volatile"] = true;
        return this;
      }
      /**
       * Sets a modifier for a subsequent event emission that the callback will be called with an error when the
       * given number of milliseconds have elapsed without an acknowledgement from the server:
       *
       * ```
       * socket.timeout(5000).emit("my-event", (err) => {
       *   if (err) {
       *     // the server did not acknowledge the event in the given delay
       *   }
       * });
       * ```
       *
       * @returns self
       * @public
       */

    }, {
      key: "timeout",
      value: function timeout(_timeout) {
        this.flags.timeout = _timeout;
        return this;
      }
      /**
       * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
       * callback.
       *
       * @param listener
       * @public
       */

    }, {
      key: "onAny",
      value: function onAny(listener) {
        this._anyListeners = this._anyListeners || [];

        this._anyListeners.push(listener);

        return this;
      }
      /**
       * Adds a listener that will be fired when any event is emitted. The event name is passed as the first argument to the
       * callback. The listener is added to the beginning of the listeners array.
       *
       * @param listener
       * @public
       */

    }, {
      key: "prependAny",
      value: function prependAny(listener) {
        this._anyListeners = this._anyListeners || [];

        this._anyListeners.unshift(listener);

        return this;
      }
      /**
       * Removes the listener that will be fired when any event is emitted.
       *
       * @param listener
       * @public
       */

    }, {
      key: "offAny",
      value: function offAny(listener) {
        if (!this._anyListeners) {
          return this;
        }

        if (listener) {
          var listeners = this._anyListeners;

          for (var i = 0; i < listeners.length; i++) {
            if (listener === listeners[i]) {
              listeners.splice(i, 1);
              return this;
            }
          }
        } else {
          this._anyListeners = [];
        }

        return this;
      }
      /**
       * Returns an array of listeners that are listening for any event that is specified. This array can be manipulated,
       * e.g. to remove listeners.
       *
       * @public
       */

    }, {
      key: "listenersAny",
      value: function listenersAny() {
        return this._anyListeners || [];
      }
    }]);

    return Socket;
  }(Emitter_1);

  /**
   * Expose `Backoff`.
   */

  var backo2 = Backoff;
  /**
   * Initialize backoff timer with `opts`.
   *
   * - `min` initial timeout in milliseconds [100]
   * - `max` max timeout [10000]
   * - `jitter` [0]
   * - `factor` [2]
   *
   * @param {Object} opts
   * @api public
   */

  function Backoff(opts) {
    opts = opts || {};
    this.ms = opts.min || 100;
    this.max = opts.max || 10000;
    this.factor = opts.factor || 2;
    this.jitter = opts.jitter > 0 && opts.jitter <= 1 ? opts.jitter : 0;
    this.attempts = 0;
  }
  /**
   * Return the backoff duration.
   *
   * @return {Number}
   * @api public
   */


  Backoff.prototype.duration = function () {
    var ms = this.ms * Math.pow(this.factor, this.attempts++);

    if (this.jitter) {
      var rand = Math.random();
      var deviation = Math.floor(rand * this.jitter * ms);
      ms = (Math.floor(rand * 10) & 1) == 0 ? ms - deviation : ms + deviation;
    }

    return Math.min(ms, this.max) | 0;
  };
  /**
   * Reset the number of attempts.
   *
   * @api public
   */


  Backoff.prototype.reset = function () {
    this.attempts = 0;
  };
  /**
   * Set the minimum duration
   *
   * @api public
   */


  Backoff.prototype.setMin = function (min) {
    this.ms = min;
  };
  /**
   * Set the maximum duration
   *
   * @api public
   */


  Backoff.prototype.setMax = function (max) {
    this.max = max;
  };
  /**
   * Set the jitter
   *
   * @api public
   */


  Backoff.prototype.setJitter = function (jitter) {
    this.jitter = jitter;
  };

  var Manager = /*#__PURE__*/function (_Emitter) {
    _inherits(Manager, _Emitter);

    var _super = _createSuper(Manager);

    function Manager(uri, opts) {
      var _this;

      _classCallCheck(this, Manager);

      var _a;

      _this = _super.call(this);
      _this.nsps = {};
      _this.subs = [];

      if (uri && "object" === _typeof(uri)) {
        opts = uri;
        uri = undefined;
      }

      opts = opts || {};
      opts.path = opts.path || "/socket.io";
      _this.opts = opts;
      installTimerFunctions(_assertThisInitialized(_this), opts);

      _this.reconnection(opts.reconnection !== false);

      _this.reconnectionAttempts(opts.reconnectionAttempts || Infinity);

      _this.reconnectionDelay(opts.reconnectionDelay || 1000);

      _this.reconnectionDelayMax(opts.reconnectionDelayMax || 5000);

      _this.randomizationFactor((_a = opts.randomizationFactor) !== null && _a !== void 0 ? _a : 0.5);

      _this.backoff = new backo2({
        min: _this.reconnectionDelay(),
        max: _this.reconnectionDelayMax(),
        jitter: _this.randomizationFactor()
      });

      _this.timeout(null == opts.timeout ? 20000 : opts.timeout);

      _this._readyState = "closed";
      _this.uri = uri;

      var _parser = opts.parser || parser;

      _this.encoder = new _parser.Encoder();
      _this.decoder = new _parser.Decoder();
      _this._autoConnect = opts.autoConnect !== false;
      if (_this._autoConnect) _this.open();
      return _this;
    }

    _createClass(Manager, [{
      key: "reconnection",
      value: function reconnection(v) {
        if (!arguments.length) return this._reconnection;
        this._reconnection = !!v;
        return this;
      }
    }, {
      key: "reconnectionAttempts",
      value: function reconnectionAttempts(v) {
        if (v === undefined) return this._reconnectionAttempts;
        this._reconnectionAttempts = v;
        return this;
      }
    }, {
      key: "reconnectionDelay",
      value: function reconnectionDelay(v) {
        var _a;

        if (v === undefined) return this._reconnectionDelay;
        this._reconnectionDelay = v;
        (_a = this.backoff) === null || _a === void 0 ? void 0 : _a.setMin(v);
        return this;
      }
    }, {
      key: "randomizationFactor",
      value: function randomizationFactor(v) {
        var _a;

        if (v === undefined) return this._randomizationFactor;
        this._randomizationFactor = v;
        (_a = this.backoff) === null || _a === void 0 ? void 0 : _a.setJitter(v);
        return this;
      }
    }, {
      key: "reconnectionDelayMax",
      value: function reconnectionDelayMax(v) {
        var _a;

        if (v === undefined) return this._reconnectionDelayMax;
        this._reconnectionDelayMax = v;
        (_a = this.backoff) === null || _a === void 0 ? void 0 : _a.setMax(v);
        return this;
      }
    }, {
      key: "timeout",
      value: function timeout(v) {
        if (!arguments.length) return this._timeout;
        this._timeout = v;
        return this;
      }
      /**
       * Starts trying to reconnect if reconnection is enabled and we have not
       * started reconnecting yet
       *
       * @private
       */

    }, {
      key: "maybeReconnectOnOpen",
      value: function maybeReconnectOnOpen() {
        // Only try to reconnect if it's the first time we're connecting
        if (!this._reconnecting && this._reconnection && this.backoff.attempts === 0) {
          // keeps reconnection from firing twice for the same reconnection loop
          this.reconnect();
        }
      }
      /**
       * Sets the current transport `socket`.
       *
       * @param {Function} fn - optional, callback
       * @return self
       * @public
       */

    }, {
      key: "open",
      value: function open(fn) {
        var _this2 = this;

        if (~this._readyState.indexOf("open")) return this;
        this.engine = new Socket$1(this.uri, this.opts);
        var socket = this.engine;
        var self = this;
        this._readyState = "opening";
        this.skipReconnect = false; // emit `open`

        var openSubDestroy = on(socket, "open", function () {
          self.onopen();
          fn && fn();
        }); // emit `error`

        var errorSub = on(socket, "error", function (err) {
          self.cleanup();
          self._readyState = "closed";

          _this2.emitReserved("error", err);

          if (fn) {
            fn(err);
          } else {
            // Only do this if there is no fn to handle the error
            self.maybeReconnectOnOpen();
          }
        });

        if (false !== this._timeout) {
          var timeout = this._timeout;

          if (timeout === 0) {
            openSubDestroy(); // prevents a race condition with the 'open' event
          } // set timer


          var timer = this.setTimeoutFn(function () {
            openSubDestroy();
            socket.close(); // @ts-ignore

            socket.emit("error", new Error("timeout"));
          }, timeout);

          if (this.opts.autoUnref) {
            timer.unref();
          }

          this.subs.push(function subDestroy() {
            clearTimeout(timer);
          });
        }

        this.subs.push(openSubDestroy);
        this.subs.push(errorSub);
        return this;
      }
      /**
       * Alias for open()
       *
       * @return self
       * @public
       */

    }, {
      key: "connect",
      value: function connect(fn) {
        return this.open(fn);
      }
      /**
       * Called upon transport open.
       *
       * @private
       */

    }, {
      key: "onopen",
      value: function onopen() {
        // clear old subs
        this.cleanup(); // mark as open

        this._readyState = "open";
        this.emitReserved("open"); // add new subs

        var socket = this.engine;
        this.subs.push(on(socket, "ping", this.onping.bind(this)), on(socket, "data", this.ondata.bind(this)), on(socket, "error", this.onerror.bind(this)), on(socket, "close", this.onclose.bind(this)), on(this.decoder, "decoded", this.ondecoded.bind(this)));
      }
      /**
       * Called upon a ping.
       *
       * @private
       */

    }, {
      key: "onping",
      value: function onping() {
        this.emitReserved("ping");
      }
      /**
       * Called with data.
       *
       * @private
       */

    }, {
      key: "ondata",
      value: function ondata(data) {
        this.decoder.add(data);
      }
      /**
       * Called when parser fully decodes a packet.
       *
       * @private
       */

    }, {
      key: "ondecoded",
      value: function ondecoded(packet) {
        this.emitReserved("packet", packet);
      }
      /**
       * Called upon socket error.
       *
       * @private
       */

    }, {
      key: "onerror",
      value: function onerror(err) {
        this.emitReserved("error", err);
      }
      /**
       * Creates a new socket for the given `nsp`.
       *
       * @return {Socket}
       * @public
       */

    }, {
      key: "socket",
      value: function socket(nsp, opts) {
        var socket = this.nsps[nsp];

        if (!socket) {
          socket = new Socket(this, nsp, opts);
          this.nsps[nsp] = socket;
        }

        return socket;
      }
      /**
       * Called upon a socket close.
       *
       * @param socket
       * @private
       */

    }, {
      key: "_destroy",
      value: function _destroy(socket) {
        var nsps = Object.keys(this.nsps);

        for (var _i = 0, _nsps = nsps; _i < _nsps.length; _i++) {
          var nsp = _nsps[_i];
          var _socket = this.nsps[nsp];

          if (_socket.active) {
            return;
          }
        }

        this._close();
      }
      /**
       * Writes a packet.
       *
       * @param packet
       * @private
       */

    }, {
      key: "_packet",
      value: function _packet(packet) {
        var encodedPackets = this.encoder.encode(packet);

        for (var i = 0; i < encodedPackets.length; i++) {
          this.engine.write(encodedPackets[i], packet.options);
        }
      }
      /**
       * Clean up transport subscriptions and packet buffer.
       *
       * @private
       */

    }, {
      key: "cleanup",
      value: function cleanup() {
        this.subs.forEach(function (subDestroy) {
          return subDestroy();
        });
        this.subs.length = 0;
        this.decoder.destroy();
      }
      /**
       * Close the current socket.
       *
       * @private
       */

    }, {
      key: "_close",
      value: function _close() {
        this.skipReconnect = true;
        this._reconnecting = false;
        this.onclose("forced close");
        if (this.engine) this.engine.close();
      }
      /**
       * Alias for close()
       *
       * @private
       */

    }, {
      key: "disconnect",
      value: function disconnect() {
        return this._close();
      }
      /**
       * Called upon engine close.
       *
       * @private
       */

    }, {
      key: "onclose",
      value: function onclose(reason) {
        this.cleanup();
        this.backoff.reset();
        this._readyState = "closed";
        this.emitReserved("close", reason);

        if (this._reconnection && !this.skipReconnect) {
          this.reconnect();
        }
      }
      /**
       * Attempt a reconnection.
       *
       * @private
       */

    }, {
      key: "reconnect",
      value: function reconnect() {
        var _this3 = this;

        if (this._reconnecting || this.skipReconnect) return this;
        var self = this;

        if (this.backoff.attempts >= this._reconnectionAttempts) {
          this.backoff.reset();
          this.emitReserved("reconnect_failed");
          this._reconnecting = false;
        } else {
          var delay = this.backoff.duration();
          this._reconnecting = true;
          var timer = this.setTimeoutFn(function () {
            if (self.skipReconnect) return;

            _this3.emitReserved("reconnect_attempt", self.backoff.attempts); // check again for the case socket closed in above events


            if (self.skipReconnect) return;
            self.open(function (err) {
              if (err) {
                self._reconnecting = false;
                self.reconnect();

                _this3.emitReserved("reconnect_error", err);
              } else {
                self.onreconnect();
              }
            });
          }, delay);

          if (this.opts.autoUnref) {
            timer.unref();
          }

          this.subs.push(function subDestroy() {
            clearTimeout(timer);
          });
        }
      }
      /**
       * Called upon successful reconnect.
       *
       * @private
       */

    }, {
      key: "onreconnect",
      value: function onreconnect() {
        var attempt = this.backoff.attempts;
        this._reconnecting = false;
        this.backoff.reset();
        this.emitReserved("reconnect", attempt);
      }
    }]);

    return Manager;
  }(Emitter_1);

  /**
   * Managers cache.
   */

  var cache = {};

  function lookup(uri, opts) {
    if (_typeof(uri) === "object") {
      opts = uri;
      uri = undefined;
    }

    opts = opts || {};
    var parsed = url(uri, opts.path || "/socket.io");
    var source = parsed.source;
    var id = parsed.id;
    var path = parsed.path;
    var sameNamespace = cache[id] && path in cache[id]["nsps"];
    var newConnection = opts.forceNew || opts["force new connection"] || false === opts.multiplex || sameNamespace;
    var io;

    if (newConnection) {
      io = new Manager(source, opts);
    } else {
      if (!cache[id]) {
        cache[id] = new Manager(source, opts);
      }

      io = cache[id];
    }

    if (parsed.query && !opts.query) {
      opts.query = parsed.queryKey;
    }

    return io.socket(parsed.path, opts);
  } // so that "lookup" can be used both as a function (e.g. `io(...)`) and as a
  // namespace (e.g. `io.connect(...)`), for backward compatibility


  _extends(lookup, {
    Manager: Manager,
    Socket: Socket,
    io: lookup,
    connect: lookup
  });

  return lookup;

}));
//# sourceMappingURL=socket.io.js.map