JavaScript事件委托案例

<!DOCTYPE html>
<html lang="en">
<head>
   <meta charset="UTF-8">
   <title>Document</title>
</head>
<body>
   <ul id="myLinks">
       <li id="goSomewhere">Go something2</li>
       <li id="doSomething">do something2</li>
       <li id="sayHi">say Hi2</li>
   </ul>
   <script>
       // var myLinks = document.querySelector("#myLinks");
       // myLinks.onclick = function(e)
       // {
       //    var target = e.target;
       //    alert(target.innerHTML);
       // }
       var EventUtil = {
       addHandler: function (element, type, handler) {//添加事件
       if (element.addEventListener) {//使用DOM2级方法添加事件
       element.addEventListener(type, handler, false);
       } else if (element.attachEvent) {//使用IE方法添加事件
       element.attachEvent("on" + type, handler);
       } else {
       element["on" + type] = handler;
       }
       },
       removeHandler: function (element, type, handler) {//取消事件
       if (element.removeEventListener) {
       element.removeEventListener(type, handler, false);
       } else if (element.detachEvent) {
       element.detachEvent("on" + type, handler);
       } else {
       element["on" + type] = null;
       }
       },

       getEvent: function (event) {//使用这个方法跨浏览器取得event对象
       return event ? event : window.event;
       },
       getTarget: function (event) {//返回事件的实际目标
       return event.target || event.srcElement;
       },
       preventDefault: function (event) {//阻止事件的默认行为
       if (event.preventDefault) {
       event.preventDefault();
       } else {
       event.returnValue = false;
       }
       },
       stopPropagation: function (event) {//立即停止事件在DOM中的传播
       if (event.stopPropagation) {
       event.stopPropagation();
       } else {
       event.cancelBubbles = true;
       }
       },
       getRelatedTarget: function (event) {//获取mouseover和mouseout相关元素
       if (event.relatedTarger) {
       return event.relatedTarget;
       } else if (event.toElement) {
       return event.toElement;
       } else if (event.fromElement) {
       return event.fromElement;
       } else { return null; }

       },
       getButton:function(event){ //获取mousedown或mouseup按下或释放的按钮是鼠标中的哪一个
       if(document.implementation.hasFeature("MouseEvents","2.0")){
           return event.button;
       }
       else{
           switch(event.button){ //将IE模型下的button属性映射为DOM模型下的button属性
           case 0:
           case 1:
           case 3:
           case 5:
           case 7:
           return 0; //按下的是鼠标主按钮（一般是左键）
           case 2:
           case 6:
           return 2; //按下的是中间的鼠标按钮
           case 4:
           return 1; //鼠标次按钮（一般是右键）
           }
           }
       },

       getWheelDelta:function(event){ //获取表示鼠标滚轮滚动方向的数值
       if(event.wheelDelta){
       return event.wheelDelta;
       }else{
       return -event.detail*40;
       }
       },

       getCharCode:function(event){ //以跨浏览器取得相同的字符编码，需在keypress事件中使用
       if(typeof event.charCode=="number"){
       return event.charCode;
       }else{
       return event.keyCode;
       }
       }

       }
       EventUtil.addHandler(window, 'load', function(event){
           var list = document.getElementById("myLinks");
           EventUtil.addHandler(list, 'click', function(event){
               event = EventUtil.getEvent(event);
               var target = EventUtil.getTarget(event);
               switch(target.id)
               {
                   case 'doSomething':
                       document.title = "I change the title!";
                       break;
                   case 'goSomewhere':
                       location.href = "http://www.baidu.com";
                       break;
                   case 'sayHi':
                       alert("Hi!");
                       break;
               }
           })
       })
   </script>
</body>
</html>

JavaScript事件委托案例

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