事件冒泡，事件捕获和事件委托

  <div >
    <div class="child" ></div>
  </div>
    document.getElementById('parent').addEventListener('click',function(e){
      console.log(e)
      console.log(this.id + '被触发')

    },true);
    document.getElementById('child').addEventListener('click', function(e){
      console.log(e)
      console.log(this.id + '被触发')
    },true
    )

事件冒泡：4-7

事件捕获：1-4

https://www.cnblogs.com/Chen-XiaoJun/p/6210987.html