Javascript Event（事件）的传播与冒泡

Z时代
2024-01-10
分类：综合

特性说明和原理图：

标准浏览器和Ie9+浏览器都支持事件的冒泡和捕获，而IE8-浏览器只支持冒泡

标准和Ie9+浏览器用stopPropagation()或cancelBubble阻止事件传播，而ie8-用e.cancelBubble属性来阻冒泡，注意ie9不支持cancelBubble属性（设置后不生效），但chrome、safari、opera、firefox都支持cancelBubble属性。

Ie8-用attachEvent为dom元素添加一个事件，但必须在事件名前加上on，此类事件只能在元素的冒泡阶段。

stopPropagatin()方法用于阻止事件的传播，如果设置在捕获阶段，则目标和冒泡阶段不会被执行；

cancelBubble属性只能阻止冒泡阶段，对捕获和目标阶段的事件不能阻止

preventDefault()和window.event.returnValue用于标准浏览器和ie9+，都可以阻止默认事件。ie8-可以用returnValue，preventDefault()。

示例代码(ie8-示例不提供)

html代码


<body class="body" > 
 <div class="log"></div>
 <input type="text" id="inTxt" name="intxt" />
<div class="wrap">
 <div class="cont">
  <button type="button" class="button" id="btn">按钮</button>
  <select name="stopType" id="stopType">
    <option value="1">StopPropagation</option>
    <option value="2">cancelBubble</option>
  </select>
  <button type="button" class="button" id="btnReject">cont阻止捕获或冒泡</button>
 </div>
</div>
</body>

层级关系：body->wrap->cont->button，可以对照上面的原理

Js代码


$(function(){
    var $log = $('.log'), 
      $wrap = $('.wrap'),
      $cont = $('.cont'),
      $btn = document.getElementById('btn'),
      $stopType = $('#stopType'),
      $body = $('body'),
      $inTxt = $('#inTxt'),
      $btnReject = $('#btnReject');
    var ePhase = ["","捕获","目标","冒泡"]
    var setBorderColor = function( $dom, color, time,event){
      $dom = $($dom);
      $log.html($log.html() + $dom.attr('class') + '[' + ePhase[event.eventPhase] + ']' + '<br/>')
      var timeIndex = window.setTimeout(function(){   
      $dom.css({
        'borderColor': color,
        'borderWidth': '4px'
      });
      }, time);
    }  
    //捕获
    $body[0].addEventListener('click',function(event){ 
      $log.html($log.html() + "-------------------<br>");
      setBorderColor($body,'#0866ff ',0,event);
    },true);  
    $wrap[0].addEventListener('click',function(event){
      setBorderColor($wrap,'yellow',2000,event); 
    },true);
    $cont[0].addEventListener('click',function(event){
      event = event || window.event;
      if( $stopType.val() == '1' ){
        event.stopPropagation();
      }else{
        event.cancelBubble = true;
      }
      setBorderColor($cont,'green',1000,event);  
    },true); 
    $btn.addEventListener('click', function(event){ 
      setBorderColor($btn,'red',0,event);
    },true);
    $btnReject[0].addEventListener('click',function(event){ 
      setBorderColor($btnReject,'gray ',0,event);
    },true);
    //冒泡
    $body[0].addEventListener('click',function(event){
      setBorderColor($body,'#0866ff ',0,event);
    },false); 
    $wrap[0].addEventListener('click',function(event){
      setBorderColor($wrap,'yellow',2000,event); 
    },false); 
    $cont[0].addEventListener('click',function(event){
      setBorderColor($cont,'green',1000,event);  
    },false); 
    $btn.addEventListener('click', function(event){ 
      setBorderColor($btn,'red',0,event);
    },false);
    $btnReject[0].addEventListener('click',function(event){ 
      setBorderColor($btnReject,'gray ',0,event);
    },false);
    //阻止默认事件
    $inTxt.keypress(function(event){
      //event.preventDefault(); 
      window.event.returnValue = false;
      $body.append( String.fromCharCode( event.keyCode ));
    });
  });