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node_modules/node-http-xhr/lib/node-event-target.js

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+'use strict';
+
+/**
+ * Node.js `EventTarget` implementation using Node's `EventEmitter`.
+ *
+ * @module node-event-target
+ * @author Stan Zhang <stan.zhang2@gmail.com>
+ */
+
+var EventEmitter = require('events').EventEmitter;
+
+/**
+ * Creates a new `EventTarget`.
+ *
+ * @classdesc The interface implemented by objects that can receive events and
+ * may have listeners for them.
+ *
+ * See {@link
+ * https://developer.mozilla.org/en-US/docs/Web/API/EventTarget
+ * `EventTarget` on MDN
+ * } for more details.
+ *
+ * @class
+ */
+module.exports = function () {
+  EventEmitter.call(this);
+};
+
+/** @alias module:node-event-target */
+var EventTarget = module.exports;
+
+//
+// Inherit some EventEmitter functions as private functions
+//
+['on', 'removeListener', 'emit', 'listeners'].forEach(function (key) {
+  Object.defineProperty(EventTarget.prototype, '_' + key, {
+    value: EventEmitter.prototype[key]
+  });
+});
+
+Object.defineProperty(EventTarget.prototype, '_listenerCount', {
+  value: 'listenerCount' in EventEmitter.prototype
+  ? EventEmitter.prototype.listenerCount
+  // Shim `EventEmitter#listenerCount` support
+  : function (event) {
+    return this._listeners(event).length;
+  }
+});
+
+//
+// Wrap the event listener methods so that the `EventEmitter` events are not
+// exposed.
+//
+
+/**
+ * Adds an event listener.
+ *
+ * @see {@link
+ * https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener
+ * `EventTarget.addEventListener` on MDN
+ * }
+ * @param {String} type - The event type.
+ * @param {Function} listener - The callback.
+ * @param {Object} [options] - Options for the listener.
+ * @param {Boolean} [options.once=false] - Invoke listener once.
+ */
+EventTarget.prototype.addEventListener = function (type, listener, options) {
+  // Re-implement `#once()` behavior
+  // This is necessary because the built-in `#once()` calls functions that we've
+  // renamed on the prototype.
+  var fired = false;
+
+  /** @this NodeHttpXHR */
+  function onceListener() {
+    this._removeListener(type, onceListener);
+
+    if (!fired) {
+      fired = true;
+      listener.apply(this, arguments);
+    }
+  }
+
+  this._on(type, options && options.once
+    ? onceListener
+    : listener
+  );
+};
+
+/**
+ * Removes an event listener.
+ *
+ * @see {@link
+ * https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/removeEventListener
+ * `EventTarget.removeEventListener` on MDN
+ * }
+ * @param {String} type - The event type.
+ * @param {Function} listener - The callback.
+ */
+EventTarget.prototype.removeEventListener = function (type, listener) {
+  this._removeListener(type, listener);
+};
+
+/**
+ * Dispatches an event.
+ *
+ * @see {@link
+ * https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/dispatchEvent
+ * `EventTarget.dispatchEvent` on MDN
+ * }
+ * @param {Object} event - The event to dispatch.
+ */
+EventTarget.prototype.dispatchEvent = function (event) {
+  event.target = this;
+  this._emit(event.type, event);
+};
+