[major] Overhaul event classes

- Remove non-standard `OpenEvent` class.
- Make properties read-only.
- Update constructor signatures to match the ones defined by the HTML
  standard.

lib/event-target.js

@@ -2,112 +2,171 @@
 
 const { kForOnEventAttribute, kListener } = require('./constants');
 
+const kCode = Symbol('kCode');
+const kData = Symbol('kData');
+const kError = Symbol('kError');
+const kMessage = Symbol('kMessage');
+const kReason = Symbol('kReason');
+const kTarget = Symbol('kTarget');
+const kType = Symbol('kType');
+const kWasClean = Symbol('kWasClean');
+
 /**
  * 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
+   * @throws {TypeError} If the `type` argument is not specified
    */
-  constructor(type, target) {
-    this.target = target;
-    this.type = type;
+  constructor(type) {
+    this[kTarget] = null;
+    this[kType] = type;
   }
-}
 
-/**
- * Class representing a message event.
- *
- * @extends Event
- * @private
- */
-class MessageEvent extends Event {
   /**
-   * Create a new `MessageEvent`.
-   *
-   * @param {(String|Buffer|ArrayBuffer|Buffer[])} data The received data
-   * @param {WebSocket} target A reference to the target to which the event was
-   *     dispatched
+   * @type {*}
    */
-  constructor(data, target) {
-    super('message', target);
+  get target() {
+    return this[kTarget];
+  }
 
-    this.data = data;
+  /**
+   * @type {String}
+   */
+  get type() {
+    return this[kType];
   }
 }
 
+Object.defineProperty(Event.prototype, 'target', { enumerable: true });
+Object.defineProperty(Event.prototype, 'type', { enumerable: true });
+
 /**
  * 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
+   * @param {String} type The name of the event
+   * @param {Object} [options] A dictionary object that allows for setting
+   *     attributes via object members of the same name
+   * @param {Number} [options.code=0] The status code explaining why the
+   *     connection was closed
+   * @param {String} [options.reason=''] A human-readable string explaining why
+   *     the connection was closed
+   * @param {Boolean} [options.wasClean=false] Indicates whether or not the
+   *     connection was cleanly closed
    */
-  constructor(code, reason, target) {
-    super('close', target);
+  constructor(type, options = {}) {
+    super(type);
 
-    this.wasClean = target._closeFrameReceived && target._closeFrameSent;
-    this.reason = reason;
-    this.code = code;
+    this[kCode] = options.code === undefined ? 0 : options.code;
+    this[kReason] = options.reason === undefined ? '' : options.reason;
+    this[kWasClean] = options.wasClean === undefined ? false : options.wasClean;
+  }
+
+  /**
+   * @type {Number}
+   */
+  get code() {
+    return this[kCode];
+  }
+
+  /**
+   * @type {String}
+   */
+  get reason() {
+    return this[kReason];
+  }
+
+  /**
+   * @type {Boolean}
+   */
+  get wasClean() {
+    return this[kWasClean];
   }
 }
 
+Object.defineProperty(CloseEvent.prototype, 'code', { enumerable: true });
+Object.defineProperty(CloseEvent.prototype, 'reason', { enumerable: true });
+Object.defineProperty(CloseEvent.prototype, 'wasClean', { enumerable: true });
+
 /**
- * Class representing an open event.
+ * Class representing an error event.
  *
  * @extends Event
- * @private
  */
-class OpenEvent extends Event {
+class ErrorEvent extends Event {
   /**
-   * Create a new `OpenEvent`.
+   * Create a new `ErrorEvent`.
    *
-   * @param {WebSocket} target A reference to the target to which the event was
-   *     dispatched
+   * @param {String} type The name of the event
+   * @param {Object} [options] A dictionary object that allows for setting
+   *     attributes via object members of the same name
+   * @param {*} [options.error=null] The error that generated this event
+   * @param {String} [options.message=''] The error message
+   */
+  constructor(type, options = {}) {
+    super(type);
+
+    this[kError] = options.error === undefined ? null : options.error;
+    this[kMessage] = options.message === undefined ? '' : options.message;
+  }
+
+  /**
+   * @type {*}
+   */
+  get error() {
+    return this[kError];
+  }
+
+  /**
+   * @type {String}
    */
-  constructor(target) {
-    super('open', target);
+  get message() {
+    return this[kMessage];
   }
 }
 
+Object.defineProperty(ErrorEvent.prototype, 'error', { enumerable: true });
+Object.defineProperty(ErrorEvent.prototype, 'message', { enumerable: true });
+
 /**
- * Class representing an error event.
+ * Class representing a message event.
  *
  * @extends Event
- * @private
  */
-class ErrorEvent extends Event {
+class MessageEvent extends Event {
   /**
-   * Create a new `ErrorEvent`.
+   * Create a new `MessageEvent`.
    *
-   * @param {Object} error The error that generated this event
-   * @param {WebSocket} target A reference to the target to which the event was
-   *     dispatched
+   * @param {String} type The name of the event
+   * @param {Object} [options] A dictionary object that allows for setting
+   *     attributes via object members of the same name
+   * @param {*} [options.data=null] The message content
    */
-  constructor(error, target) {
-    super('error', target);
+  constructor(type, options = {}) {
+    super(type);
+
+    this[kData] = options.data === undefined ? null : options.data;
+  }
 
-    this.message = error.message;
-    this.error = error;
+  /**
+   * @type {*}
+   */
+  get data() {
+    return this[kData];
   }
 }
 
+Object.defineProperty(MessageEvent.prototype, 'data', { enumerable: true });
+
 /**
  * This provides methods for emulating the `EventTarget` interface. It's not
  * meant to be used directly.
@@ -132,20 +191,40 @@ const EventTarget = {
 
     if (type === 'message') {
       wrapper = function onMessage(data, isBinary) {
-        const event = new MessageEvent(isBinary ? data : data.toString(), this);
+        const event = new MessageEvent('message', {
+          data: isBinary ? data : data.toString()
+        });
+
+        event[kTarget] = this;
         listener.call(this, event);
       };
     } else if (type === 'close') {
       wrapper = function onClose(code, message) {
-        listener.call(this, new CloseEvent(code, message.toString(), this));
+        const event = new CloseEvent('close', {
+          code,
+          reason: message.toString(),
+          wasClean: this._closeFrameReceived && this._closeFrameSent
+        });
+
+        event[kTarget] = this;
+        listener.call(this, event);
       };
     } else if (type === 'error') {
       wrapper = function onError(error) {
-        listener.call(this, new ErrorEvent(error, this));
+        const event = new ErrorEvent('error', {
+          error,
+          message: error.message
+        });
+
+        event[kTarget] = this;
+        listener.call(this, event);
       };
     } else if (type === 'open') {
       wrapper = function onOpen() {
-        listener.call(this, new OpenEvent(this));
+        const event = new Event('open');
+
+        event[kTarget] = this;
+        listener.call(this, event);
       };
     } else {
       return;
@@ -178,4 +257,10 @@ const EventTarget = {
   }
 };
 
-module.exports = EventTarget;
+module.exports = {
+  CloseEvent,
+  ErrorEvent,
+  Event,
+  EventTarget,
+  MessageEvent
+};

lib/websocket.js

@@ -21,7 +21,9 @@ const {
   kWebSocket,
   NOOP
 } = require('./constants');
-const { addEventListener, removeEventListener } = require('./event-target');
+const {
+  EventTarget: { addEventListener, removeEventListener }
+} = require('./event-target');
 const { format, parse } = require('./extension');
 const { toBuffer } = require('./buffer-util');