[No00006A]Js的addEventListener()及attachEvent()区别分析【js中的事件监听】
1.添加时间监听：
Chrom中：
addEventListener的使用方式：
target.addEventListener(type, listener, useCapture);
target： 文档节点、document、window 或 XMLHttpRequest。
type： 字符串，事件名称，不含"on"，比如"click"、"mouseover"、"keydown"等。
listener ：实现了 EventListener 接口或者是 JavaScript 中的函数。
useCapture ：是否使用捕捉，看了后面的事件流一节后就明白了，一般用 false 。
事件触发时，会将一个 Event 对象传递给事件处理程序，比如： document.getElementById("testText").addEventListener("keydown", function (event) { alert(event.keyCode); }, false);
IE中：
target.attachEvent(type, listener);
target： 文档节点、document、window 或 XMLHttpRequest。
type： 字符串，事件名称，含"on"，比如"onclick"、"onmouseover"、"onkeydown"等。
listener ：实现了 EventListener 接口或者是 JavaScript 中的函数。 例如：document.getElementById("txt").attachEvent("onclick",function(event){alert(event.keyCode);});
两者使用的原理：可对执行的优先级不一样，下面实例讲解如下：
a.attachEvent方法，为某一事件附加其它的处理事件。（不支持Chrome系列）
document.getElementById("btn").onclick = method1;
document.getElementById("btn").onclick = method2;
document.getElementById("btn").onclick = method3;//如果这样写,那么将会只有medhot3被执行
如果写成这样：
var btn1Obj = document.getElementById("btn1"); //object.attachEvent(event,function); btn1Obj.attachEvent("onclick",method1); btn1Obj.attachEvent("onclick",method2); btn1Obj.attachEvent("onclick",method3);//执行顺序为method3->method2->method1
b.addEventListener方法 用于 Chrome系列
如果是Chrome系列，并不支持该方法，需要用到addEventListener
var btn1Obj = document.getElementById("btn1"); //element.addEventListener(type,listener,useCapture); btn1Obj.addEventListener("click",method1,false); btn1Obj.addEventListener("click",method2,false); btn1Obj.addEventListener("click",method3,false);//执行顺序为method1->method2->method3
所以要兼容Chrome和IE，要写if判断，举例：(要注意的是div必须放到js前面才行，文件编码为utf-8）
<html> <head> <meta charset="utf-8"> </head> <body> <div id="name1" style="border:1px solid red;padding:10px 10px 10px 10px;" style="border:1px solid red;padding:10px 10px 10px 10px;"> <div id="name2" style="border:1px solid green;padding:10px 10px 10px 10px;" style="border:1px solid green;padding:10px 10px 10px 10px;"> 点击 </div> </div> <div id="info"> </div> <script type="text/javascript"> var name1 = document.getElementById('name1'); //要注意 var name2 = document.getElementById('name2'); //要注意 var info = document.getElementById('info'); if (name1.attachEvent) { //对于attachEvent前面的target我们一定要保证不为空 name1.attachEvent('onclick', function() { info.innerHTML += "红色" + "<br>"; }); name2.attachEvent('onclick', function() { info.innerHTML += "绿色" + "<br>"; }); } else { name1.addEventListener('click', function() { info.innerHTML += "红色" + "<br>"; }, false); name2.addEventListener('click', function() { info.innerHTML += "绿色" + "<br>"; }, false); } </script> </body> </html>
那为什么会有含"on"和不含"on"的问题？
答案要从W3C的发展时间轴来看, DOM(Document Object Model)的模型可以分为两种, DOM 0 及 DOM 2. 从数字来看就可以知道DOM 0 当然是比较旧的协议, 我们直接来看DOM2 :
|
DOM 0&DOM1 协定 Event(Event Name) |
DOM 2 Event |
Description |
|
onblur() |
blur |
The element has lost focus (that is, it is not selected by the user). |
|
onchange() |
change |
The element has either changed (such as by typing into a text field) or the element has lost focus. |
|
onclick() |
click |
The mouse has been clicked on an element. |
|
ondblclick() |
dblclick |
The mouse has been double-clicked on an element. |
|
onfocus() |
focus |
The element has gotten focus. |
|
onkeydown() |
keydown |
A keyboard key has been pressed down (as opposed to released) while the element has focus. |
|
onkeypress() |
keypress |
A keyboard key has been pressed while the element has focus. |
|
onkeyup() |
keyup |
A keyboard key has been released while the element has focus. |
|
onload() |
load |
The element has loaded (document, frameset, or image). |
|
onmousedown() |
mousedown |
A mouse button has been pressed. |
|
onmousemove() |
mousemove |
The mouse has been moved. |
|
onmouseout() |
mouseout |
The mouse has been moved off of or away from an element. |
|
onmouseover() |
mouseover |
The mouse has moved over an element. |
|
onmouseup() |
mouseup |
A mouse button has been released. |
|
onreset() |
|
The form element has been reset, such as when a form reset button is pressed. |
|
onresize() |
|
The window's size has been changed. |
|
onselect() |
|
The text of a form element has been selected. |
|
onsubmit() |
submit |
The form has been submitted. |
|
onunload() |
unload |
The document or frameset has been unloaded. |
addEventListener()这个函数只支持新的DOM2 ：addEventListener(event,function,capture/bubble);
参数event如上表（DOM 2 Event）所示, function是要执行的函数, capture与bubble分别是W3C制定得两种时间模式,简单来说capture就是从document的开始读到最后一行, 再执行事件, 而bubble则是先寻找指定的位置再执行事件.
capture/bubble的参数是布尔值, True表示用capture, False则是bubble.
Windows Internet Explorer对应的EventHandler, 是 attachEvent(), 格式如下:
window.attachEvent("submit",myFunction());
比较特别的是attachEvent不需要指定capture/bubble的参数, 因为在windows IE环境下都是使用Bubble的模式.这里用个例子来表现事件的用法:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title> Rollover </title> <script type="text/javascript"> function moveOver(imgObj) { if (typeof window.addEventListener != "undefined") { imgObj.addEventListener("mouseover", function() { imgObj.src = imgObj.id + "_over.png"; }, false); imgObj.addEventListener("mouseout", function() { imgObj.src = imgObj.id + "_default.png"; }, false); } else { imgObj.attachEvent("onmouseover", function() { imgObj.src = imgObj.id + "_over.png"; }); imgObj.attachEvent("onmouseout", function() { imgObj.src = imgObj.id + "_default.png"; }); } } function rollover() { var images = document.getElementsByTagName("img"); var roll = new RegExp("rollover"); var preload = []; for (var i = 0; i < images.length; i++) { if (images[i].id.match(roll)) { preload[i] = new Image(); preload[i].src = images[i].id + "_over.png"; moveOver(images[i]); } } } if (typeof window.addEventListener != "undefined") { window.addEventListener("load", rollover, false); } else { window.attachEvent("onload", rollover) } </script> </head> <body> <p> <img id="rollover_home" name="img_home" src="rollover_home_default.png" alt="Home"> </p> <p> <img id="rollover_about" name="img_about" src="rollover_about_default.png" alt="About"> </p> <p> <img id="rollover_blog" name="img_blog" src="rollover_blog_default.png" alt="Blog"> </p> <p> <img id="logo" name="img_logo" src="logo.png" alt="Braingia Logo"> </p> </body> </html>
ps：你需要图片素材下载：[No00006A]图片素材.7z
上述的 typeof window.addEventListener != "undefined" 程序代码可以判断使用者的浏览器是否支持AddEventListener这个事件模型, 如果不支持就使用attachEvent.
2.移除事件监听：
W3C 及 IE 同时支持移除指定的事件, 用途是移除设定的事件, 格式分别如下:
W3C格式:
removeEventListener(event,function,capture/bubble);
Windows IE的格式如下:
detachEvent(event,function);
