jquery.fileupload.js

/*
 * jQuery File Upload Plugin
 * https://github.com/blueimp/jQuery-File-Upload
 *
 * Copyright 2010, Sebastian Tschan
 * https://blueimp.net
 *
 * Licensed under the MIT license:
 * https://opensource.org/licenses/MIT
 */

/* global define, require */
/* eslint-disable new-cap */

(function(factory) {
  'use strict';
  if (typeof define === 'function' && define.amd) {
    // Register as an anonymous AMD module:
    define(['jquery', 'jquery-ui/ui/widget'], factory);
  } else if (typeof exports === 'object') {
    // Node/CommonJS:
    factory(require('jquery'), require('./vendor/jquery.ui.widget'));
  } else {
    // Browser globals:
    factory(window.jQuery);
  }
})(function($) {
  'use strict';

  // Detect file input support, based on
  // https://viljamis.com/2012/file-upload-support-on-mobile/
  $.support.fileInput = !(
    new RegExp(
      // Handle devices which give false positives for the feature detection:
      '(Android (1\\.[0156]|2\\.[01]))' +
        '|(Windows Phone (OS 7|8\\.0))|(XBLWP)|(ZuneWP)|(WPDesktop)' +
        '|(w(eb)?OSBrowser)|(webOS)' +
        '|(Kindle/(1\\.0|2\\.[05]|3\\.0))'
    ).test(window.navigator.userAgent) ||
    // Feature detection for all other devices:
    $('<input type="file"/>').prop('disabled')
  );

  // The FileReader API is not actually used, but works as feature detection,
  // as some Safari versions (5?) support XHR file uploads via the FormData API,
  // but not non-multipart XHR file uploads.
  // window.XMLHttpRequestUpload is not available on IE10, so we check for
  // window.ProgressEvent instead to detect XHR2 file upload capability:
  $.support.xhrFileUpload = !!(window.ProgressEvent && window.FileReader);
  $.support.xhrFormDataFileUpload = !!window.FormData;

  // Detect support for Blob slicing (required for chunked uploads):
  $.support.blobSlice =
    window.Blob &&
    (Blob.prototype.slice ||
      Blob.prototype.webkitSlice ||
      Blob.prototype.mozSlice);

  /**
   * Helper function to create drag handlers for dragover/dragenter/dragleave
   *
   * @param {string} type Event type
   * @returns {Function} Drag handler
   */
  function getDragHandler(type) {
    var isDragOver = type === 'dragover';
    return function(e) {
      e.dataTransfer = e.originalEvent && e.originalEvent.dataTransfer;
      var dataTransfer = e.dataTransfer;
      if (
        dataTransfer &&
        $.inArray('Files', dataTransfer.types) !== -1 &&
        this._trigger(type, $.Event(type, { delegatedEvent: e })) !== false
      ) {
        e.preventDefault();
        if (isDragOver) {
          dataTransfer.dropEffect = 'copy';
        }
      }
    };
  }

  // The fileupload widget listens for change events on file input fields defined
  // via fileInput setting and paste or drop events of the given dropZone.
  // In addition to the default jQuery Widget methods, the fileupload widget
  // exposes the "add" and "send" methods, to add or directly send files using
  // the fileupload API.
  // By default, files added via file input selection, paste, drag & drop or
  // "add" method are uploaded immediately, but it is possible to override
  // the "add" callback option to queue file uploads.
  $.widget('blueimp.fileupload', {
    options: {
      // The drop target element(s), by the default the complete document.
      // Set to null to disable drag & drop support:
      dropZone: $(document),
      // The paste target element(s), by the default undefined.
      // Set to a DOM node or jQuery object to enable file pasting:
      pasteZone: undefined,
      // The file input field(s), that are listened to for change events.
      // If undefined, it is set to the file input fields inside
      // of the widget element on plugin initialization.
      // Set to null to disable the change listener.
      fileInput: undefined,
      // By default, the file input field is replaced with a clone after
      // each input field change event. This is required for iframe transport
      // queues and allows change events to be fired for the same file
      // selection, but can be disabled by setting the following option to false:
      replaceFileInput: true,
      // The parameter name for the file form data (the request argument name).
      // If undefined or empty, the name property of the file input field is
      // used, or "files[]" if the file input name property is also empty,
      // can be a string or an array of strings:
      paramName: undefined,
      // By default, each file of a selection is uploaded using an individual
      // request for XHR type uploads. Set to false to upload file
      // selections in one request each:
      singleFileUploads: true,
      // To limit the number of files uploaded with one XHR request,
      // set the following option to an integer greater than 0:
      limitMultiFileUploads: undefined,
      // The following option limits the number of files uploaded with one
      // XHR request to keep the request size under or equal to the defined
      // limit in bytes:
      limitMultiFileUploadSize: undefined,
      // Multipart file uploads add a number of bytes to each uploaded file,
      // therefore the following option adds an overhead for each file used
      // in the limitMultiFileUploadSize configuration:
      limitMultiFileUploadSizeOverhead: 512,
      // Set the following option to true to issue all file upload requests
      // in a sequential order:
      sequentialUploads: false,
      // To limit the number of concurrent uploads,
      // set the following option to an integer greater than 0:
      limitConcurrentUploads: undefined,
      // Set the following option to true to force iframe transport uploads:
      forceIframeTransport: false,
      // Set the following option to the location of a redirect url on the
      // origin server, for cross-domain iframe transport uploads:
      redirect: undefined,
      // The parameter name for the redirect url, sent as part of the form
      // data and set to 'redirect' if this option is empty:
      redirectParamName: undefined,
      // Set the following option to the location of a postMessage window,
      // to enable postMessage transport uploads:
      postMessage: undefined,
      // By default, XHR file uploads are sent as multipart/form-data.
      // The iframe transport is always using multipart/form-data.
      // Set to false to enable non-multipart XHR uploads:
      multipart: true,
      // To upload large files in smaller chunks, set the following option
      // to a preferred maximum chunk size. If set to 0, null or undefined,
      // or the browser does not support the required Blob API, files will
      // be uploaded as a whole.
      maxChunkSize: undefined,
      // When a non-multipart upload or a chunked multipart upload has been
      // aborted, this option can be used to resume the upload by setting
      // it to the size of the already uploaded bytes. This option is most
      // useful when modifying the options object inside of the "add" or
      // "send" callbacks, as the options are cloned for each file upload.
      uploadedBytes: undefined,
      // By default, failed (abort or error) file uploads are removed from the
      // global progress calculation. Set the following option to false to
      // prevent recalculating the global progress data:
      recalculateProgress: true,
      // Interval in milliseconds to calculate and trigger progress events:
      progressInterval: 100,
      // Interval in milliseconds to calculate progress bitrate:
      bitrateInterval: 500,
      // By default, uploads are started automatically when adding files:
      autoUpload: true,
      // By default, duplicate file names are expected to be handled on
      // the server-side. If this is not possible (e.g. when uploading
      // files directly to Amazon S3), the following option can be set to
      // an empty object or an object mapping existing filenames, e.g.:
      // { "image.jpg": true, "image (1).jpg": true }
      // If it is set, all files will be uploaded with unique filenames,
      // adding increasing number suffixes if necessary, e.g.:
      // "image (2).jpg"
      uniqueFilenames: undefined,

      // Error and info messages:
      messages: {
        uploadedBytes: 'Uploaded bytes exceed file size'
      },

      // Translation function, gets the message key to be translated
      // and an object with context specific data as arguments:
      i18n: function(message, context) {
        // eslint-disable-next-line no-param-reassign
        message = this.messages[message] || message.toString();
        if (context) {
          $.each(context, function(key, value) {
            // eslint-disable-next-line no-param-reassign
            message = message.replace('{' + key + '}', value);
          });
        }
        return message;
      },

      // Additional form data to be sent along with the file uploads can be set
      // using this option, which accepts an array of objects with name and
      // value properties, a function returning such an array, a FormData
      // object (for XHR file uploads), or a simple object.
      // The form of the first fileInput is given as parameter to the function:
      formData: function(form) {
        return form.serializeArray();
      },

      // The add callback is invoked as soon as files are added to the fileupload
      // widget (via file input selection, drag & drop, paste or add API call).
      // If the singleFileUploads option is enabled, this callback will be
      // called once for each file in the selection for XHR file uploads, else
      // once for each file selection.
      //
      // The upload starts when the submit method is invoked on the data parameter.
      // The data object contains a files property holding the added files
      // and allows you to override plugin options as well as define ajax settings.
      //
      // Listeners for this callback can also be bound the following way:
      // .bind('fileuploadadd', func);
      //
      // data.submit() returns a Promise object and allows to attach additional
      // handlers using jQuery's Deferred callbacks:
      // data.submit().done(func).fail(func).always(func);
      add: function(e, data) {
        if (e.isDefaultPrevented()) {
          return false;
        }
        if (
          data.autoUpload ||
          (data.autoUpload !== false &&
            $(this).fileupload('option', 'autoUpload'))
        ) {
          data.process().done(function() {
            data.submit();
          });
        }
      },

      // Other callbacks:

      // Callback for the submit event of each file upload:
      // submit: function (e, data) {}, // .bind('fileuploadsubmit', func);

      // Callback for the start of each file upload request:
      // send: function (e, data) {}, // .bind('fileuploadsend', func);

      // Callback for successful uploads:
      // done: function (e, data) {}, // .bind('fileuploaddone', func);

      // Callback for failed (abort or error) uploads:
      // fail: function (e, data) {}, // .bind('fileuploadfail', func);

      // Callback for completed (success, abort or error) requests:
      // always: function (e, data) {}, // .bind('fileuploadalways', func);

      // Callback for upload progress events:
      // progress: function (e, data) {}, // .bind('fileuploadprogress', func);

      // Callback for global upload progress events:
      // progressall: function (e, data) {}, // .bind('fileuploadprogressall', func);

      // Callback for uploads start, equivalent to the global ajaxStart event:
      // start: function (e) {}, // .bind('fileuploadstart', func);

      // Callback for uploads stop, equivalent to the global ajaxStop event:
      // stop: function (e) {}, // .bind('fileuploadstop', func);

      // Callback for change events of the fileInput(s):
      // change: function (e, data) {}, // .bind('fileuploadchange', func);

      // Callback for paste events to the pasteZone(s):
      // paste: function (e, data) {}, // .bind('fileuploadpaste', func);

      // Callback for drop events of the dropZone(s):
      // drop: function (e, data) {}, // .bind('fileuploaddrop', func);

      // Callback for dragover events of the dropZone(s):
      // dragover: function (e) {}, // .bind('fileuploaddragover', func);

      // Callback before the start of each chunk upload request (before form data initialization):
      // chunkbeforesend: function (e, data) {}, // .bind('fileuploadchunkbeforesend', func);

      // Callback for the start of each chunk upload request:
      // chunksend: function (e, data) {}, // .bind('fileuploadchunksend', func);

      // Callback for successful chunk uploads:
      // chunkdone: function (e, data) {}, // .bind('fileuploadchunkdone', func);

      // Callback for failed (abort or error) chunk uploads:
      // chunkfail: function (e, data) {}, // .bind('fileuploadchunkfail', func);

      // Callback for completed (success, abort or error) chunk upload requests:
      // chunkalways: function (e, data) {}, // .bind('fileuploadchunkalways', func);

      // The plugin options are used as settings object for the ajax calls.
      // The following are jQuery ajax settings required for the file uploads:
      processData: false,
      contentType: false,
      cache: false,
      timeout: 0
    },

    // A list of options that require reinitializing event listeners and/or
    // special initialization code:
    _specialOptions: [
      'fileInput',
      'dropZone',
      'pasteZone',
      'multipart',
      'forceIframeTransport'
    ],

    _blobSlice:
      $.support.blobSlice &&
      function() {
        var slice = this.slice || this.webkitSlice || this.mozSlice;
        return slice.apply(this, arguments);
      },

    _BitrateTimer: function() {
      this.timestamp = Date.now ? Date.now() : new Date().getTime();
      this.loaded = 0;
      this.bitrate = 0;
      this.getBitrate = function(now, loaded, interval) {
        var timeDiff = now - this.timestamp;
        if (!this.bitrate || !interval || timeDiff > interval) {
          this.bitrate = (loaded - this.loaded) * (1000 / timeDiff) * 8;
          this.loaded = loaded;
          this.timestamp = now;
        }
        return this.bitrate;
      };
    },

    _isXHRUpload: function(options) {
      return (
        !options.forceIframeTransport &&
        ((!options.multipart && $.support.xhrFileUpload) ||
          $.support.xhrFormDataFileUpload)
      );
    },

    _getFormData: function(options) {
      var formData;
      if ($.type(options.formData) === 'function') {
        return options.formData(options.form);
      }
      if ($.isArray(options.formData)) {
        return options.formData;
      }
      if ($.type(options.formData) === 'object') {
        formData = [];
        $.each(options.formData, function(name, value) {
          formData.push({ name: name, value: value });
        });
        return formData;
      }
      return [];
    },

    _getTotal: function(files) {
      var total = 0;
      $.each(files, function(index, file) {
        total += file.size || 1;
      });
      return total;
    },

    _initProgressObject: function(obj) {
      var progress = {
        loaded: 0,
        total: 0,
        bitrate: 0
      };
      if (obj._progress) {
        $.extend(obj._progress, progress);
      } else {
        obj._progress = progress;
      }
    },

    _initResponseObject: function(obj) {
      var prop;
      if (obj._response) {
        for (prop in obj._response) {
          if (Object.prototype.hasOwnProperty.call(obj._response, prop)) {
            delete obj._response[prop];
          }
        }
      } else {
        obj._response = {};
      }
    },

    _onProgress: function(e, data) {
      if (e.lengthComputable) {
        var now = Date.now ? Date.now() : new Date().getTime(),
          loaded;
        if (
          data._time &&
          data.progressInterval &&
          now - data._time < data.progressInterval &&
          e.loaded !== e.total
        ) {
          return;
        }
        data._time = now;
        loaded =
          Math.floor(
            (e.loaded / e.total) * (data.chunkSize || data._progress.total)
          ) + (data.uploadedBytes || 0);
        // Add the difference from the previously loaded state
        // to the global loaded counter:
        this._progress.loaded += loaded - data._progress.loaded;
        this._progress.bitrate = this._bitrateTimer.getBitrate(
          now,
          this._progress.loaded,
          data.bitrateInterval
        );
        data._progress.loaded = data.loaded = loaded;
        data._progress.bitrate = data.bitrate = data._bitrateTimer.getBitrate(
          now,
          loaded,
          data.bitrateInterval
        );
        // Trigger a custom progress event with a total data property set
        // to the file size(s) of the current upload and a loaded data
        // property calculated accordingly:
        this._trigger(
          'progress',
          $.Event('progress', { delegatedEvent: e }),
          data
        );
        // Trigger a global progress event for all current file uploads,
        // including ajax calls queued for sequential file uploads:
        this._trigger(
          'progressall',
          $.Event('progressall', { delegatedEvent: e }),
          this._progress
        );
      }
    },

    _initProgressListener: function(options) {
      var that = this,
        xhr = options.xhr ? options.xhr() : $.ajaxSettings.xhr();
      // Accesss to the native XHR object is required to add event listeners
      // for the upload progress event:
      if (xhr.upload) {
        $(xhr.upload).bind('progress', function(e) {
          var oe = e.originalEvent;
          // Make sure the progress event properties get copied over:
          e.lengthComputable = oe.lengthComputable;
          e.loaded = oe.loaded;
          e.total = oe.total;
          that._onProgress(e, options);
        });
        options.xhr = function() {
          return xhr;
        };
      }
    },

    _deinitProgressListener: function(options) {
      var xhr = options.xhr ? options.xhr() : $.ajaxSettings.xhr();
      if (xhr.upload) {
        $(xhr.upload).unbind('progress');
      }
    },

    _isInstanceOf: function(type, obj) {
      // Cross-frame instanceof check
      return Object.prototype.toString.call(obj) === '[object ' + type + ']';
    },

    _getUniqueFilename: function(name, map) {
      // eslint-disable-next-line no-param-reassign
      name = String(name);
      if (map[name]) {
        // eslint-disable-next-line no-param-reassign
        name = name.replace(/(?: \(([\d]+)\))?(\.[^.]+)?$/, function(
          _,
          p1,
          p2
        ) {
          var index = p1 ? Number(p1) + 1 : 1;
          var ext = p2 || '';
          return ' (' + index + ')' + ext;
        });
        return this._getUniqueFilename(name, map);
      }
      map[name] = true;
      return name;
    },

    _initXHRData: function(options) {
      var that = this,
        formData,
        file = options.files[0],
        // Ignore non-multipart setting if not supported:
        multipart = options.multipart || !$.support.xhrFileUpload,
        paramName =
          $.type(options.paramName) === 'array'
            ? options.paramName[0]
            : options.paramName;
      options.headers = $.extend({}, options.headers);
      if (options.contentRange) {
        options.headers['Content-Range'] = options.contentRange;
      }
      if (!multipart || options.blob || !this._isInstanceOf('File', file)) {
        options.headers['Content-Disposition'] =
          'attachment; filename="' +
          encodeURI(file.uploadName || file.name) +
          '"';
      }
      if (!multipart) {
        options.contentType = file.type || 'application/octet-stream';
        options.data = options.blob || file;
      } else if ($.support.xhrFormDataFileUpload) {
        if (options.postMessage) {
          // window.postMessage does not allow sending FormData
          // objects, so we just add the File/Blob objects to
          // the formData array and let the postMessage window
          // create the FormData object out of this array:
          formData = this._getFormData(options);
          if (options.blob) {
            formData.push({
              name: paramName,
              value: options.blob
            });
          } else {
            $.each(options.files, function(index, file) {
              formData.push({
                name:
                  ($.type(options.paramName) === 'array' &&
                    options.paramName[index]) ||
                  paramName,
                value: file
              });
            });
          }
        } else {
          if (that._isInstanceOf('FormData', options.formData)) {
            formData = options.formData;
          } else {
            formData = new FormData();
            $.each(this._getFormData(options), function(index, field) {
              formData.append(field.name, field.value);
            });
          }
          if (options.blob) {
            formData.append(
              paramName,
              options.blob,
              file.uploadName || file.name
            );
          } else {
            $.each(options.files, function(index, file) {
              // This check allows the tests to run with
              // dummy objects:
              if (
                that._isInstanceOf('File', file) ||
                that._isInstanceOf('Blob', file)
              ) {
                var fileName = file.uploadName || file.name;
                if (options.uniqueFilenames) {
                  fileName = that._getUniqueFilename(
                    fileName,
                    options.uniqueFilenames
                  );
                }
                formData.append(
                  ($.type(options.paramName) === 'array' &&
                    options.paramName[index]) ||
                    paramName,
                  file,
                  fileName
                );
              }
            });
          }
        }
        options.data = formData;
      }
      // Blob reference is not needed anymore, free memory:
      options.blob = null;
    },

    _initIframeSettings: function(options) {
      var targetHost = $('<a></a>')
        .prop('href', options.url)
        .prop('host');
      // Setting the dataType to iframe enables the iframe transport:
      options.dataType = 'iframe ' + (options.dataType || '');
      // The iframe transport accepts a serialized array as form data:
      options.formData = this._getFormData(options);
      // Add redirect url to form data on cross-domain uploads:
      if (options.redirect && targetHost && targetHost !== location.host) {
        options.formData.push({
          name: options.redirectParamName || 'redirect',
          value: options.redirect
        });
      }
    },

    _initDataSettings: function(options) {
      if (this._isXHRUpload(options)) {
        if (!this._chunkedUpload(options, true)) {
          if (!options.data) {
            this._initXHRData(options);
          }
          this._initProgressListener(options);
        }
        if (options.postMessage) {
          // Setting the dataType to postmessage enables the
          // postMessage transport:
          options.dataType = 'postmessage ' + (options.dataType || '');
        }
      } else {
        this._initIframeSettings(options);
      }
    },

    _getParamName: function(options) {
      var fileInput = $(options.fileInput),
        paramName = options.paramName;
      if (!paramName) {
        paramName = [];
        fileInput.each(function() {
          var input = $(this),
            name = input.prop('name') || 'files[]',
            i = (input.prop('files') || [1]).length;
          while (i) {
            paramName.push(name);
            i -= 1;
          }
        });
        if (!paramName.length) {
          paramName = [fileInput.prop('name') || 'files[]'];
        }
      } else if (!$.isArray(paramName)) {
        paramName = [paramName];
      }
      return paramName;
    },

    _initFormSettings: function(options) {
      // Retrieve missing options from the input field and the
      // associated form, if available:
      if (!options.form || !options.form.length) {
        options.form = $(options.fileInput.prop('form'));
        // If the given file input doesn't have an associated form,
        // use the default widget file input's form:
        if (!options.form.length) {
          options.form = $(this.options.fileInput.prop('form'));
        }
      }
      options.paramName = this._getParamName(options);
      if (!options.url) {
        options.url = options.form.prop('action') || location.href;
      }
      // The HTTP request method must be "POST" or "PUT":
      options.type = (
        options.type ||
        ($.type(options.form.prop('method')) === 'string' &&
          options.form.prop('method')) ||
        ''
      ).toUpperCase();
      if (
        options.type !== 'POST' &&
        options.type !== 'PUT' &&
        options.type !== 'PATCH'
      ) {
        options.type = 'POST';
      }
      if (!options.formAcceptCharset) {
        options.formAcceptCharset = options.form.attr('accept-charset');
      }
    },

    _getAJAXSettings: function(data) {
      var options = $.extend({}, this.options, data);
      this._initFormSettings(options);
      this._initDataSettings(options);
      return options;
    },

    // jQuery 1.6 doesn't provide .state(),
    // while jQuery 1.8+ removed .isRejected() and .isResolved():
    _getDeferredState: function(deferred) {
      if (deferred.state) {
        return deferred.state();
      }
      if (deferred.isResolved()) {
        return 'resolved';
      }
      if (deferred.isRejected()) {
        return 'rejected';
      }
      return 'pending';
    },

    // Maps jqXHR callbacks to the equivalent
    // methods of the given Promise object:
    _enhancePromise: function(promise) {
      promise.success = promise.done;
      promise.error = promise.fail;
      promise.complete = promise.always;
      return promise;
    },

    // Creates and returns a Promise object enhanced with
    // the jqXHR methods abort, success, error and complete:
    _getXHRPromise: function(resolveOrReject, context, args) {
      var dfd = $.Deferred(),
        promise = dfd.promise();
      // eslint-disable-next-line no-param-reassign
      context = context || this.options.context || promise;
      if (resolveOrReject === true) {
        dfd.resolveWith(context, args);
      } else if (resolveOrReject === false) {
        dfd.rejectWith(context, args);
      }
      promise.abort = dfd.promise;
      return this._enhancePromise(promise);
    },

    // Adds convenience methods to the data callback argument:
    _addConvenienceMethods: function(e, data) {
      var that = this,
        getPromise = function(args) {
          return $.Deferred()
            .resolveWith(that, args)
            .promise();
        };
      data.process = function(resolveFunc, rejectFunc) {
        if (resolveFunc || rejectFunc) {
          data._processQueue = this._processQueue = (
            this._processQueue || getPromise([this])
          )
            .then(function() {
              if (data.errorThrown) {
                return $.Deferred()
                  .rejectWith(that, [data])
                  .promise();
              }
              return getPromise(arguments);
            })
            .then(resolveFunc, rejectFunc);
        }
        return this._processQueue || getPromise([this]);
      };
      data.submit = function() {
        if (this.state() !== 'pending') {
          data.jqXHR = this.jqXHR =
            that._trigger(
              'submit',
              $.Event('submit', { delegatedEvent: e }),
              this
            ) !== false && that._onSend(e, this);
        }
        return this.jqXHR || that._getXHRPromise();
      };
      data.abort = function() {
        if (this.jqXHR) {
          return this.jqXHR.abort();
        }
        this.errorThrown = 'abort';
        that._trigger('fail', null, this);
        return that._getXHRPromise(false);
      };
      data.state = function() {
        if (this.jqXHR) {
          return that._getDeferredState(this.jqXHR);
        }
        if (this._processQueue) {
          return that._getDeferredState(this._processQueue);
        }
      };
      data.processing = function() {
        return (
          !this.jqXHR &&
          this._processQueue &&
          that._getDeferredState(this._processQueue) === 'pending'
        );
      };
      data.progress = function() {
        return this._progress;
      };
      data.response = function() {
        return this._response;
      };
    },

    // Parses the Range header from the server response
    // and returns the uploaded bytes:
    _getUploadedBytes: function(jqXHR) {
      var range = jqXHR.getResponseHeader('Range'),
        parts = range && range.split('-'),
        upperBytesPos = parts && parts.length > 1 && parseInt(parts[1], 10);
      return upperBytesPos && upperBytesPos + 1;
    },

    // Uploads a file in multiple, sequential requests
    // by splitting the file up in multiple blob chunks.
    // If the second parameter is true, only tests if the file
    // should be uploaded in chunks, but does not invoke any
    // upload requests:
    _chunkedUpload: function(options, testOnly) {
      options.uploadedBytes = options.uploadedBytes || 0;
      var that = this,
        file = options.files[0],
        fs = file.size,
        ub = options.uploadedBytes,
        mcs = options.maxChunkSize || fs,
        slice = this._blobSlice,
        dfd = $.Deferred(),
        promise = dfd.promise(),
        jqXHR,
        upload;
      if (
        !(
          this._isXHRUpload(options) &&
          slice &&
          (ub || ($.type(mcs) === 'function' ? mcs(options) : mcs) < fs)
        ) ||
        options.data
      ) {
        return false;
      }
      if (testOnly) {
        return true;
      }
      if (ub >= fs) {
        file.error = options.i18n('uploadedBytes');
        return this._getXHRPromise(false, options.context, [
          null,
          'error',
          file.error
        ]);
      }
      // The chunk upload method:
      upload = function() {
        // Clone the options object for each chunk upload:
        var o = $.extend({}, options),
          currentLoaded = o._progress.loaded;
        o.blob = slice.call(
          file,
          ub,
          ub + ($.type(mcs) === 'function' ? mcs(o) : mcs),
          file.type
        );
        // Store the current chunk size, as the blob itself
        // will be dereferenced after data processing:
        o.chunkSize = o.blob.size;
        // Expose the chunk bytes position range:
        o.contentRange =
          'bytes ' + ub + '-' + (ub + o.chunkSize - 1) + '/' + fs;
        // Trigger chunkbeforesend to allow form data to be updated for this chunk
        that._trigger('chunkbeforesend', null, o);
        // Process the upload data (the blob and potential form data):
        that._initXHRData(o);
        // Add progress listeners for this chunk upload:
        that._initProgressListener(o);
        jqXHR = (
          (that._trigger('chunksend', null, o) !== false && $.ajax(o)) ||
          that._getXHRPromise(false, o.context)
        )
          .done(function(result, textStatus, jqXHR) {
            ub = that._getUploadedBytes(jqXHR) || ub + o.chunkSize;
            // Create a progress event if no final progress event
            // with loaded equaling total has been triggered
            // for this chunk:
            if (currentLoaded + o.chunkSize - o._progress.loaded) {
              that._onProgress(
                $.Event('progress', {
                  lengthComputable: true,
                  loaded: ub - o.uploadedBytes,
                  total: ub - o.uploadedBytes
                }),
                o
              );
            }
            options.uploadedBytes = o.uploadedBytes = ub;
            o.result = result;
            o.textStatus = textStatus;
            o.jqXHR = jqXHR;
            that._trigger('chunkdone', null, o);
            that._trigger('chunkalways', null, o);
            if (ub < fs) {
              // File upload not yet complete,
              // continue with the next chunk:
              upload();
            } else {
              dfd.resolveWith(o.context, [result, textStatus, jqXHR]);
            }
          })
          .fail(function(jqXHR, textStatus, errorThrown) {
            o.jqXHR = jqXHR;
            o.textStatus = textStatus;
            o.errorThrown = errorThrown;
            that._trigger('chunkfail', null, o);
            that._trigger('chunkalways', null, o);
            dfd.rejectWith(o.context, [jqXHR, textStatus, errorThrown]);
          })
          .always(function() {
            that._deinitProgressListener(o);
          });
      };
      this._enhancePromise(promise);
      promise.abort = function() {
        return jqXHR.abort();
      };
      upload();
      return promise;
    },

    _beforeSend: function(e, data) {
      if (this._active === 0) {
        // the start callback is triggered when an upload starts
        // and no other uploads are currently running,
        // equivalent to the global ajaxStart event:
        this._trigger('start');
        // Set timer for global bitrate progress calculation:
        this._bitrateTimer = new this._BitrateTimer();
        // Reset the global progress values:
        this._progress.loaded = this._progress.total = 0;
        this._progress.bitrate = 0;
      }
      // Make sure the container objects for the .response() and
      // .progress() methods on the data object are available
      // and reset to their initial state:
      this._initResponseObject(data);
      this._initProgressObject(data);
      data._progress.loaded = data.loaded = data.uploadedBytes || 0;
      data._progress.total = data.total = this._getTotal(data.files) || 1;
      data._progress.bitrate = data.bitrate = 0;
      this._active += 1;
      // Initialize the global progress values:
      this._progress.loaded += data.loaded;
      this._progress.total += data.total;
    },

    _onDone: function(result, textStatus, jqXHR, options) {
      var total = options._progress.total,
        response = options._response;
      if (options._progress.loaded < total) {
        // Create a progress event if no final progress event
        // with loaded equaling total has been triggered:
        this._onProgress(
          $.Event('progress', {
            lengthComputable: true,
            loaded: total,
            total: total
          }),
          options
        );
      }
      response.result = options.result = result;
      response.textStatus = options.textStatus = textStatus;
      response.jqXHR = options.jqXHR = jqXHR;
      this._trigger('done', null, options);
    },

    _onFail: function(jqXHR, textStatus, errorThrown, options) {
      var response = options._response;
      if (options.recalculateProgress) {
        // Remove the failed (error or abort) file upload from
        // the global progress calculation:
        this._progress.loaded -= options._progress.loaded;
        this._progress.total -= options._progress.total;
      }
      response.jqXHR = options.jqXHR = jqXHR;
      response.textStatus = options.textStatus = textStatus;
      response.errorThrown = options.errorThrown = errorThrown;
      this._trigger('fail', null, options);
    },

    _onAlways: function(jqXHRorResult, textStatus, jqXHRorError, options) {
      // jqXHRorResult, textStatus and jqXHRorError are added to the
      // options object via done and fail callbacks
      this._trigger('always', null, options);
    },

    _onSend: function(e, data) {
      if (!data.submit) {
        this._addConvenienceMethods(e, data);
      }
      var that = this,
        jqXHR,
        aborted,
        slot,
        pipe,
        options = that._getAJAXSettings(data),
        send = function() {
          that._sending += 1;
          // Set timer for bitrate progress calculation:
          options._bitrateTimer = new that._BitrateTimer();
          jqXHR =
            jqXHR ||
            (
              ((aborted ||
                that._trigger(
                  'send',
                  $.Event('send', { delegatedEvent: e }),
                  options
                ) === false) &&
                that._getXHRPromise(false, options.context, aborted)) ||
              that._chunkedUpload(options) ||
              $.ajax(options)
            )
              .done(function(result, textStatus, jqXHR) {
                that._onDone(result, textStatus, jqXHR, options);
              })
              .fail(function(jqXHR, textStatus, errorThrown) {
                that._onFail(jqXHR, textStatus, errorThrown, options);
              })
              .always(function(jqXHRorResult, textStatus, jqXHRorError) {
                that._deinitProgressListener(options);
                that._onAlways(
                  jqXHRorResult,
                  textStatus,
                  jqXHRorError,
                  options
                );
                that._sending -= 1;
                that._active -= 1;
                if (
                  options.limitConcurrentUploads &&
                  options.limitConcurrentUploads > that._sending
                ) {
                  // Start the next queued upload,
                  // that has not been aborted:
                  var nextSlot = that._slots.shift();
                  while (nextSlot) {
                    if (that._getDeferredState(nextSlot) === 'pending') {
                      nextSlot.resolve();
                      break;
                    }
                    nextSlot = that._slots.shift();
                  }
                }
                if (that._active === 0) {
                  // The stop callback is triggered when all uploads have
                  // been completed, equivalent to the global ajaxStop event:
                  that._trigger('stop');
                }
              });
          return jqXHR;
        };
      this._beforeSend(e, options);
      if (
        this.options.sequentialUploads ||
        (this.options.limitConcurrentUploads &&
          this.options.limitConcurrentUploads <= this._sending)
      ) {
        if (this.options.limitConcurrentUploads > 1) {
          slot = $.Deferred();
          this._slots.push(slot);
          pipe = slot.then(send);
        } else {
          this._sequence = this._sequence.then(send, send);
          pipe = this._sequence;
        }
        // Return the piped Promise object, enhanced with an abort method,
        // which is delegated to the jqXHR object of the current upload,
        // and jqXHR callbacks mapped to the equivalent Promise methods:
        pipe.abort = function() {
          aborted = [undefined, 'abort', 'abort'];
          if (!jqXHR) {
            if (slot) {
              slot.rejectWith(options.context, aborted);
            }
            return send();
          }
          return jqXHR.abort();
        };
        return this._enhancePromise(pipe);
      }
      return send();
    },

    _onAdd: function(e, data) {
      var that = this,
        result = true,
        options = $.extend({}, this.options, data),
        files = data.files,
        filesLength = files.length,
        limit = options.limitMultiFileUploads,
        limitSize = options.limitMultiFileUploadSize,
        overhead = options.limitMultiFileUploadSizeOverhead,
        batchSize = 0,
        paramName = this._getParamName(options),
        paramNameSet,
        paramNameSlice,
        fileSet,
        i,
        j = 0;
      if (!filesLength) {
        return false;
      }
      if (limitSize && files[0].size === undefined) {
        limitSize = undefined;
      }
      if (
        !(options.singleFileUploads || limit || limitSize) ||
        !this._isXHRUpload(options)
      ) {
        fileSet = [files];
        paramNameSet = [paramName];
      } else if (!(options.singleFileUploads || limitSize) && limit) {
        fileSet = [];
        paramNameSet = [];
        for (i = 0; i < filesLength; i += limit) {
          fileSet.push(files.slice(i, i + limit));
          paramNameSlice = paramName.slice(i, i + limit);
          if (!paramNameSlice.length) {
            paramNameSlice = paramName;
          }
          paramNameSet.push(paramNameSlice);
        }
      } else if (!options.singleFileUploads && limitSize) {
        fileSet = [];
        paramNameSet = [];
        for (i = 0; i < filesLength; i = i + 1) {
          batchSize += files[i].size + overhead;
          if (
            i + 1 === filesLength ||
            batchSize + files[i + 1].size + overhead > limitSize ||
            (limit && i + 1 - j >= limit)
          ) {
            fileSet.push(files.slice(j, i + 1));
            paramNameSlice = paramName.slice(j, i + 1);
            if (!paramNameSlice.length) {
              paramNameSlice = paramName;
            }
            paramNameSet.push(paramNameSlice);
            j = i + 1;
            batchSize = 0;
          }
        }
      } else {
        paramNameSet = paramName;
      }
      data.originalFiles = files;
      $.each(fileSet || files, function(index, element) {
        var newData = $.extend({}, data);
        newData.files = fileSet ? element : [element];
        newData.paramName = paramNameSet[index];
        that._initResponseObject(newData);
        that._initProgressObject(newData);
        that._addConvenienceMethods(e, newData);
        result = that._trigger(
          'add',
          $.Event('add', { delegatedEvent: e }),
          newData
        );
        return result;
      });
      return result;
    },

    _replaceFileInput: function(data) {
      var input = data.fileInput,
        inputClone = input.clone(true),
        restoreFocus = input.is(document.activeElement);
      // Add a reference for the new cloned file input to the data argument:
      data.fileInputClone = inputClone;
      $('<form></form>')
        .append(inputClone)[0]
        .reset();
      // Detaching allows to insert the fileInput on another form
      // without loosing the file input value:
      input.after(inputClone).detach();
      // If the fileInput had focus before it was detached,
      // restore focus to the inputClone.
      if (restoreFocus) {
        inputClone.focus();
      }
      // Avoid memory leaks with the detached file input:
      $.cleanData(input.unbind('remove'));
      // Replace the original file input element in the fileInput
      // elements set with the clone, which has been copied including
      // event handlers:
      this.options.fileInput = this.options.fileInput.map(function(i, el) {
        if (el === input[0]) {
          return inputClone[0];
        }
        return el;
      });
      // If the widget has been initialized on the file input itself,
      // override this.element with the file input clone:
      if (input[0] === this.element[0]) {
        this.element = inputClone;
      }
    },

    _handleFileTreeEntry: function(entry, path) {
      var that = this,
        dfd = $.Deferred(),
        entries = [],
        dirReader,
        errorHandler = function(e) {
          if (e && !e.entry) {
            e.entry = entry;
          }
          // Since $.when returns immediately if one
          // Deferred is rejected, we use resolve instead.
          // This allows valid files and invalid items
          // to be returned together in one set:
          dfd.resolve([e]);
        },
        successHandler = function(entries) {
          that
            ._handleFileTreeEntries(entries, path + entry.name + '/')
            .done(function(files) {
              dfd.resolve(files);
            })
            .fail(errorHandler);
        },
        readEntries = function() {
          dirReader.readEntries(function(results) {
            if (!results.length) {
              successHandler(entries);
            } else {
              entries = entries.concat(results);
              readEntries();
            }
          }, errorHandler);
        };
      // eslint-disable-next-line no-param-reassign
      path = path || '';
      if (entry.isFile) {
        if (entry._file) {
          // Workaround for Chrome bug #149735
          entry._file.relativePath = path;
          dfd.resolve(entry._file);
        } else {
          entry.file(function(file) {
            file.relativePath = path;
            dfd.resolve(file);
          }, errorHandler);
        }
      } else if (entry.isDirectory) {
        dirReader = entry.createReader();
        readEntries();
      } else {
        // Return an empty list for file system items
        // other than files or directories:
        dfd.resolve([]);
      }
      return dfd.promise();
    },

    _handleFileTreeEntries: function(entries, path) {
      var that = this;
      return $.when
        .apply(
          $,
          $.map(entries, function(entry) {
            return that._handleFileTreeEntry(entry, path);
          })
        )
        .then(function() {
          return Array.prototype.concat.apply([], arguments);
        });
    },

    _getDroppedFiles: function(dataTransfer) {
      // eslint-disable-next-line no-param-reassign
      dataTransfer = dataTransfer || {};
      var items = dataTransfer.items;
      if (
        items &&
        items.length &&
        (items[0].webkitGetAsEntry || items[0].getAsEntry)
      ) {
        return this._handleFileTreeEntries(
          $.map(items, function(item) {
            var entry;
            if (item.webkitGetAsEntry) {
              entry = item.webkitGetAsEntry();
              if (entry) {
                // Workaround for Chrome bug #149735:
                entry._file = item.getAsFile();
              }
              return entry;
            }
            return item.getAsEntry();
          })
        );
      }
      return $.Deferred()
        .resolve($.makeArray(dataTransfer.files))
        .promise();
    },

    _getSingleFileInputFiles: function(fileInput) {
      // eslint-disable-next-line no-param-reassign
      fileInput = $(fileInput);
      var entries =
          fileInput.prop('webkitEntries') || fileInput.prop('entries'),
        files,
        value;
      if (entries && entries.length) {
        return this._handleFileTreeEntries(entries);
      }
      files = $.makeArray(fileInput.prop('files'));
      if (!files.length) {
        value = fileInput.prop('value');
        if (!value) {
          return $.Deferred()
            .resolve([])
            .promise();
        }
        // If the files property is not available, the browser does not
        // support the File API and we add a pseudo File object with
        // the input value as name with path information removed:
        files = [{ name: value.replace(/^.*\\/, '') }];
      } else if (files[0].name === undefined && files[0].fileName) {
        // File normalization for Safari 4 and Firefox 3:
        $.each(files, function(index, file) {
          file.name = file.fileName;
          file.size = file.fileSize;
        });
      }
      return $.Deferred()
        .resolve(files)
        .promise();
    },

    _getFileInputFiles: function(fileInput) {
      if (!(fileInput instanceof $) || fileInput.length === 1) {
        return this._getSingleFileInputFiles(fileInput);
      }
      return $.when
        .apply($, $.map(fileInput, this._getSingleFileInputFiles))
        .then(function() {
          return Array.prototype.concat.apply([], arguments);
        });
    },

    _onChange: function(e) {
      var that = this,
        data = {
          fileInput: $(e.target),
          form: $(e.target.form)
        };
      this._getFileInputFiles(data.fileInput).always(function(files) {
        data.files = files;
        if (that.options.replaceFileInput) {
          that._replaceFileInput(data);
        }
        if (
          that._trigger(
            'change',
            $.Event('change', { delegatedEvent: e }),
            data
          ) !== false
        ) {
          that._onAdd(e, data);
        }
      });
    },

    _onPaste: function(e) {
      var items =
          e.originalEvent &&
          e.originalEvent.clipboardData &&
          e.originalEvent.clipboardData.items,
        data = { files: [] };
      if (items && items.length) {
        $.each(items, function(index, item) {
          var file = item.getAsFile && item.getAsFile();
          if (file) {
            data.files.push(file);
          }
        });
        if (
          this._trigger(
            'paste',
            $.Event('paste', { delegatedEvent: e }),
            data
          ) !== false
        ) {
          this._onAdd(e, data);
        }
      }
    },

    _onDrop: function(e) {
      e.dataTransfer = e.originalEvent && e.originalEvent.dataTransfer;
      var that = this,
        dataTransfer = e.dataTransfer,
        data = {};
      if (dataTransfer && dataTransfer.files && dataTransfer.files.length) {
        e.preventDefault();
        this._getDroppedFiles(dataTransfer).always(function(files) {
          data.files = files;
          if (
            that._trigger(
              'drop',
              $.Event('drop', { delegatedEvent: e }),
              data
            ) !== false
          ) {
            that._onAdd(e, data);
          }
        });
      }
    },

    _onDragOver: getDragHandler('dragover'),

    _onDragEnter: getDragHandler('dragenter'),

    _onDragLeave: getDragHandler('dragleave'),

    _initEventHandlers: function() {
      if (this._isXHRUpload(this.options)) {
        this._on(this.options.dropZone, {
          dragover: this._onDragOver,
          drop: this._onDrop,
          // event.preventDefault() on dragenter is required for IE10+:
          dragenter: this._onDragEnter,
          // dragleave is not required, but added for completeness:
          dragleave: this._onDragLeave
        });
        this._on(this.options.pasteZone, {
          paste: this._onPaste
        });
      }
      if ($.support.fileInput) {
        this._on(this.options.fileInput, {
          change: this._onChange
        });
      }
    },

    _destroyEventHandlers: function() {
      this._off(this.options.dropZone, 'dragenter dragleave dragover drop');
      this._off(this.options.pasteZone, 'paste');
      this._off(this.options.fileInput, 'change');
    },

    _destroy: function() {
      this._destroyEventHandlers();
    },

    _setOption: function(key, value) {
      var reinit = $.inArray(key, this._specialOptions) !== -1;
      if (reinit) {
        this._destroyEventHandlers();
      }
      this._super(key, value);
      if (reinit) {
        this._initSpecialOptions();
        this._initEventHandlers();
      }
    },

    _initSpecialOptions: function() {
      var options = this.options;
      if (options.fileInput === undefined) {
        options.fileInput = this.element.is('input[type="file"]')
          ? this.element
          : this.element.find('input[type="file"]');
      } else if (!(options.fileInput instanceof $)) {
        options.fileInput = $(options.fileInput);
      }
      if (!(options.dropZone instanceof $)) {
        options.dropZone = $(options.dropZone);
      }
      if (!(options.pasteZone instanceof $)) {
        options.pasteZone = $(options.pasteZone);
      }
    },

    _getRegExp: function(str) {
      var parts = str.split('/'),
        modifiers = parts.pop();
      parts.shift();
      return new RegExp(parts.join('/'), modifiers);
    },

    _isRegExpOption: function(key, value) {
      return (
        key !== 'url' &&
        $.type(value) === 'string' &&
        /^\/.*\/[igm]{0,3}$/.test(value)
      );
    },

    _initDataAttributes: function() {
      var that = this,
        options = this.options,
        data = this.element.data();
      // Initialize options set via HTML5 data-attributes:
      $.each(this.element[0].attributes, function(index, attr) {
        var key = attr.name.toLowerCase(),
          value;
        if (/^data-/.test(key)) {
          // Convert hyphen-ated key to camelCase:
          key = key.slice(5).replace(/-[a-z]/g, function(str) {
            return str.charAt(1).toUpperCase();
          });
          value = data[key];
          if (that._isRegExpOption(key, value)) {
            value = that._getRegExp(value);
          }
          options[key] = value;
        }
      });
    },

    _create: function() {
      this._initDataAttributes();
      this._initSpecialOptions();
      this._slots = [];
      this._sequence = this._getXHRPromise(true);
      this._sending = this._active = 0;
      this._initProgressObject(this);
      this._initEventHandlers();
    },

    // This method is exposed to the widget API and allows to query
    // the number of active uploads:
    active: function() {
      return this._active;
    },

    // This method is exposed to the widget API and allows to query
    // the widget upload progress.
    // It returns an object with loaded, total and bitrate properties
    // for the running uploads:
    progress: function() {
      return this._progress;
    },

    // This method is exposed to the widget API and allows adding files
    // using the fileupload API. The data parameter accepts an object which
    // must have a files property and can contain additional options:
    // .fileupload('add', {files: filesList});
    add: function(data) {
      var that = this;
      if (!data || this.options.disabled) {
        return;
      }
      if (data.fileInput && !data.files) {
        this._getFileInputFiles(data.fileInput).always(function(files) {
          data.files = files;
          that._onAdd(null, data);
        });
      } else {
        data.files = $.makeArray(data.files);
        this._onAdd(null, data);
      }
    },

    // This method is exposed to the widget API and allows sending files
    // using the fileupload API. The data parameter accepts an object which
    // must have a files or fileInput property and can contain additional options:
    // .fileupload('send', {files: filesList});
    // The method returns a Promise object for the file upload call.
    send: function(data) {
      if (data && !this.options.disabled) {
        if (data.fileInput && !data.files) {
          var that = this,
            dfd = $.Deferred(),
            promise = dfd.promise(),
            jqXHR,
            aborted;
          promise.abort = function() {
            aborted = true;
            if (jqXHR) {
              return jqXHR.abort();
            }
            dfd.reject(null, 'abort', 'abort');
            return promise;
          };
          this._getFileInputFiles(data.fileInput).always(function(files) {
            if (aborted) {
              return;
            }
            if (!files.length) {
              dfd.reject();
              return;
            }
            data.files = files;
            jqXHR = that._onSend(null, data);
            jqXHR.then(
              function(result, textStatus, jqXHR) {
                dfd.resolve(result, textStatus, jqXHR);
              },
              function(jqXHR, textStatus, errorThrown) {
                dfd.reject(jqXHR, textStatus, errorThrown);
              }
            );
          });
          return this._enhancePromise(promise);
        }
        data.files = $.makeArray(data.files);
        if (data.files.length) {
          return this._onSend(null, data);
        }
      }
      return this._getXHRPromise(false, data && data.context);
    }
  });
});