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Event Listener polyfill
// addEventListener polyfill IE6+
!window.addEventListener && (function (window, document) {
function Event(e, element) {
var instance = this;
for (property in e) {
instance[property] = e[property];
}
instance.currentTarget = element;
instance.target = e.srcElement || element;
instance.timeStamp = +new Date;
instance.preventDefault = function () {
e.returnValue = false;
};
instance.stopPropagation = function () {
e.cancelBubble = true;
};
}
function addEventListener(type, listener) {
var
element = this,
listeners = element.listeners = element.listeners || [],
index = listeners.push([listener, function (e) {
listener.call(element, new Event(e, element));
}]) - 1;
element.attachEvent('on' + type, listeners[index][1]);
}
function removeEventListener(type, listener) {
for (var element = this, listeners = element.listeners || [], length = listeners.length, index = 0; index < length; ++index) {
if (listeners[index][0] === listener) {
element.detachEvent('on' + type, listeners[index][1]);
}
}
}
window.addEventListener = document.addEventListener = addEventListener;
window.removeEventListener = document.removeEventListener = removeEventListener;
if ('Element' in window) {
Element.prototype.addEventListener = addEventListener;
Element.prototype.removeEventListener = removeEventListener;
} else {
var
head = document.getElementsByTagName('head')[0],
style = document.createElement('style');
head.insertBefore(style, head.firstChild);
style.styleSheet.cssText = '*{-ms-event-prototype:expression(!this.addEventListener&&(this.addEventListener=addEventListener)&&(this.removeEventListener=removeEventListener))}';
}
})(window, document) && scrollBy(0, 0);
@matthewp

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commented Jul 5, 2012

This won't work when the listener is an object. In that case addEventListener will call listener.handleEvent. Should be easy enough to fix though. Here's an explanation:

http://ajaxian.com/archives/an-alternative-way-to-addeventlistener

@Rich-Harris

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commented Jul 16, 2013

Thanks for this polyfill - the CSS expression stuff is a stroke of genius. I've forked it to use it in a project of my own (you don't specify a license but I assume that's kosher...).

There's one bit I don't quite understand: what's up with scrollBy(0, 0)? The IIFE returns undefined, so the && operator short-circuits and the code is never reached. What does it do?

@carlosascari

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commented Feb 18, 2016

Keep in mind, for...in loops are supported by IE10+. So this polyfill will not work unless you replace then with normal for(;;) loops.

@paulyn000

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commented Mar 20, 2016

will this work on DOMContentLoaded, readystatechange, progress or what?

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