aaac7fed
 liuqimichale
add
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'use strict';
/* Simplified implementation of DOM2 EventTarget.
* http://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-EventTarget
*/
function EventTarget() {
this._listeners = {};
}
EventTarget.prototype.addEventListener = function(eventType, listener) {
if (!(eventType in this._listeners)) {
this._listeners[eventType] = [];
}
var arr = this._listeners[eventType];
// #4
if (arr.indexOf(listener) === -1) {
// Make a copy so as not to interfere with a current dispatchEvent.
arr = arr.concat([listener]);
}
this._listeners[eventType] = arr;
};
EventTarget.prototype.removeEventListener = function(eventType, listener) {
var arr = this._listeners[eventType];
if (!arr) {
return;
}
var idx = arr.indexOf(listener);
if (idx !== -1) {
if (arr.length > 1) {
// Make a copy so as not to interfere with a current dispatchEvent.
this._listeners[eventType] = arr.slice(0, idx).concat(arr.slice(idx + 1));
} else {
delete this._listeners[eventType];
}
return;
}
};
EventTarget.prototype.dispatchEvent = function() {
var event = arguments[0];
var t = event.type;
// equivalent of Array.prototype.slice.call(arguments, 0);
var args = arguments.length === 1 ? [event] : Array.apply(null, arguments);
// TODO: This doesn't match the real behavior; per spec, onfoo get
// their place in line from the /first/ time they're set from
// non-null. Although WebKit bumps it to the end every time it's
// set.
if (this['on' + t]) {
this['on' + t].apply(this, args);
}
if (t in this._listeners) {
// Grab a reference to the listeners list. removeEventListener may alter the list.
var listeners = this._listeners[t];
for (var i = 0; i < listeners.length; i++) {
listeners[i].apply(this, args);
}
}
};
module.exports = EventTarget;
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