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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview EventTracker is a simple class that manages the addition and
* removal of DOM event listeners. In particular, it keeps track of all
* listeners that have been added and makes it easy to remove some or all of
* them without requiring all the information again. This is particularly handy
* when the listener is a generated function such as a lambda or the result of
* calling Function.bind.
*/
/**
* The type of the internal tracking entry. TODO(dbeam): move this back to
* EventTracker.Entry when https://github.com/google/closure-compiler/issues/544
* is fixed.
* @typedef {{target: !EventTarget,
* eventType: string,
* listener: (EventListener|Function),
* capture: boolean}}
*/
var EventTrackerEntry;
/**
* Create an EventTracker to track a set of events.
* EventTracker instances are typically tied 1:1 with other objects or
* DOM elements whose listeners should be removed when the object is disposed
* or the corresponding elements are removed from the DOM.
* @constructor
*/
function EventTracker() {
/**
* @type {Array<EventTrackerEntry>}
* @private
*/
this.listeners_ = [];
}
EventTracker.prototype = {
/**
* Add an event listener - replacement for EventTarget.addEventListener.
* @param {!EventTarget} target The DOM target to add a listener to.
* @param {string} eventType The type of event to subscribe to.
* @param {EventListener|Function} listener The listener to add.
* @param {boolean=} opt_capture Whether to invoke during the capture phase.
*/
add: function(target, eventType, listener, opt_capture) {
var capture = !!opt_capture;
var h = {
target: target,
eventType: eventType,
listener: listener,
capture: capture,
};
this.listeners_.push(h);
target.addEventListener(eventType, listener, capture);
},
/**
* Remove any specified event listeners added with this EventTracker.
* @param {!EventTarget} target The DOM target to remove a listener from.
* @param {?string} eventType The type of event to remove.
*/
remove: function(target, eventType) {
this.listeners_ = this.listeners_.filter(function(h) {
if (h.target == target && (!eventType || (h.eventType == eventType))) {
EventTracker.removeEventListener_(h);
return false;
}
return true;
});
},
/**
* Remove all event listeners added with this EventTracker.
*/
removeAll: function() {
this.listeners_.forEach(EventTracker.removeEventListener_);
this.listeners_ = [];
}
};
/**
* Remove a single event listener given it's tracking entry. It's up to the
* caller to ensure the entry is removed from listeners_.
* @param {EventTrackerEntry} h The entry describing the listener to remove.
* @private
*/
EventTracker.removeEventListener_ = function(h) {
h.target.removeEventListener(h.eventType, h.listener, h.capture);
};
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