Home Web Front-end JS Tutorial How to use JS to add events to dynamic elements

How to use JS to add events to dynamic elements

Jun 14, 2018 pm 02:49 PM
js event event delegation element Dynamically add

This time I will show you how to operate JS to add events to dynamic elements. What are the precautions for operating JS to add events to dynamic elements? The following is a practical case, let’s take a look.

We sometimes create some elements through js in daily development, but if you use the original for loop to add events to the created nodes, it often does not work:

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>js动态添加事件</title>
</head>
<body>
 <ul id="out-ul">
  <li class="out-li">123</li>
  <li class="out-li">123</li>
  <li class="out-li">123</li>
 </ul>
 <button id="btn">添加</button>
 <script>
  document.getElementById('btn').addEventListener('click',function(){
   var htmlFragment='<li>我是新增的li</li>';
   var addLi=document.createElement('li');
   addLi.innerHTML=htmlFragment;
   outUl.appendChild(addLi);
  },false);
  var outUl=document.getElementById('out-ul')
  var outLi=outUl.getElementsByClassName('out-li');
  for(var i=0;i<outLi.length;i++){
   outLi[i].onclick=function(){
    alert(1);
   }
  }
 </script>
</body>
</html>
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Running effect:

For example, the events added to li through the for loop cannot be bound to the newly added li. The detailed reasons will not be explained here. So how to solve this? In fact, the method is also simple, which is to solve it through event delegation. Directly enter the code. The above code is simply modified:

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>www.jb51.net js动态添加事件</title>
</head>
<body>
 <ul id="out-ul">
  <li class="out-li">123</li>
  <li class="out-li">123</li>
  <li class="out-li">123</li>
 </ul>
 <button id="btn">添加</button>
 <script>
  var outUl=document.getElementById('out-ul')
  var outLi=outUl.getElementsByClassName('out-li');
  document.getElementById('btn').addEventListener('click',function(){
   var htmlFragment='<li>我是新增的li</li>';
   var addLi=document.createElement('li');
   addLi.innerHTML=htmlFragment;
   outUl.appendChild(addLi);
  },false);
  outUl.addEventListener('click',function(e){
   e=e || window.event;//兼容ie
   alert(e.target.innerHTML);
  }, false);
 </script>
</body>
</html>
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I believe you have mastered the method after reading the case in this article. More Please pay attention to other related articles on the php Chinese website!

Recommended reading:

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The above is the detailed content of How to use JS to add events to dynamic elements. For more information, please follow other related articles on the PHP Chinese website!

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