[minor] Move the EventTarget methods to lib/EventTarget.js

lib/EventTarget.js

@@ -0,0 +1,158 @@
+'use strict';
+
+/**
+ * Class representing an event.
+ *
+ * @private
+ */
+class Event {
+  /**
+   * Create a new `Event`.
+   *
+   * @param {String} type The name of the event
+   * @param {Object} target A reference to the target to which the event was dispatched
+   */
+  constructor (type, target) {
+    this.target = target;
+    this.type = type;
+  }
+}
+
+/**
+ * Class representing a message event.
+ *
+ * @extends Event
+ * @private
+ */
+class MessageEvent extends Event {
+  /**
+   * Create a new `MessageEvent`.
+   *
+   * @param {(String|Buffer|ArrayBuffer)} data The received data
+   * @param {Boolean} isBinary Specifies if `data` is binary
+   * @param {WebSocket} target A reference to the target to which the event was dispatched
+   */
+  constructor (data, isBinary, target) {
+    super('message', target);
+
+    this.binary = isBinary; // non-standard.
+    this.data = data;
+  }
+}
+
+/**
+ * Class representing a close event.
+ *
+ * @extends Event
+ * @private
+ */
+class CloseEvent extends Event {
+  /**
+   * Create a new `CloseEvent`.
+   *
+   * @param {Number} code The status code explaining why the connection is being closed
+   * @param {String} reason A human-readable string explaining why the connection is closing
+   * @param {WebSocket} target A reference to the target to which the event was dispatched
+   */
+  constructor (code, reason, target) {
+    super('close', target);
+
+    this.wasClean = code === undefined || code === 1000;
+    this.reason = reason;
+    this.target = target;
+    this.type = 'close';
+    this.code = code;
+  }
+}
+
+/**
+ * Class representing an open event.
+ *
+ * @extends Event
+ * @private
+ */
+class OpenEvent extends Event {
+  /**
+   * Create a new `OpenEvent`.
+   *
+   * @param {WebSocket} target A reference to the target to which the event was dispatched
+   */
+  constructor (target) {
+    super('open', target);
+  }
+}
+
+/**
+ * This provides methods for emulating the `EventTarget` interface. It's not
+ * meant to be used directly.
+ *
+ * @mixin
+ */
+const EventTarget = {
+  /**
+   * Register an event listener.
+   *
+   * @param {String} method A string representing the event type to listen for
+   * @param {Function} listener The listener to add
+   * @public
+   */
+  addEventListener (method, listener) {
+    if (typeof listener !== 'function') return;
+
+    function onMessage (data, flags) {
+      if (flags.binary && this.binaryType === 'arraybuffer') {
+        data = new Uint8Array(data).buffer;
+      }
+      listener.call(this, new MessageEvent(data, !!flags.binary, this));
+    }
+
+    function onClose (code, message) {
+      listener.call(this, new CloseEvent(code, message, this));
+    }
+
+    function onError (event) {
+      event.type = 'error';
+      event.target = this;
+      listener.call(this, event);
+    }
+
+    function onOpen () {
+      listener.call(this, new OpenEvent(this));
+    }
+
+    if (method === 'message') {
+      onMessage._listener = listener;
+      this.on(method, onMessage);
+    } else if (method === 'close') {
+      onClose._listener = listener;
+      this.on(method, onClose);
+    } else if (method === 'error') {
+      onError._listener = listener;
+      this.on(method, onError);
+    } else if (method === 'open') {
+      onOpen._listener = listener;
+      this.on(method, onOpen);
+    } else {
+      this.on(method, listener);
+    }
+  },
+
+  /**
+   * Remove an event listener.
+   *
+   * @param {String} method A string representing the event type to remove
+   * @param {Function} listener The listener to remove
+   * @public
+   */
+  removeEventListener (method, listener) {
+    const listeners = this.listeners(method);
+
+    for (var i = 0; i < listeners.length; i++) {
+      if (listeners[i]._listener === listener) {
+        this.removeListener(method, listeners[i]);
+      }
+    }
+  }
+};
+
+module.exports = EventTarget;