知识库

html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box {
      width: 200px;
      height: 200px;
      background: skyblue;
      display: flex;
      justify-content: center;
      align-items: center;
    }

    .outer {
      width: 150px;
      height: 150px;
      background: orange;
      display: flex;
      justify-content: center;
      align-items: center;
    }

    .inner {
      width: 50px;
      height: 50px;
      background: #bfa;
    }
  </style>
</head>
<body>
  <div class="div">
    <div class="outer">
      <div class="inner"></div>
    </div>
  </div>

  <script>
    let div = document.querySelector('.div'),
      outer = document.querySelector('.outer'),
      inner = document.querySelector('.inner')

    // DOM0 事件绑定都是在冒泡阶段触发的
    // DOM2 事件绑定可以控制在捕获还是冒泡阶段触发

    inner.onclick = function (e) {
      console.log('inner')
      // e.path：冒泡的路径
      // path: Array(7)
      //   0: div.inner
      //   1: div.outer
      //   2: div.box
      //   3: body
      //   4: html
      //   5: document
      //   6: Window { ... }
    }

    outer.onclick = function () {
      console.log('outer')
    }

    // 默认为false, 在冒泡阶段触发, 如果为true, 在捕获阶段触发。
    div.addEventListener('click', () => {
      console.log('box') // 最先输出, 因为在捕获阶段触发
    }, true) 
  </script>
</body>
</html>