webComponents/demo/2-shadowDom/index.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>shadow Dom</title>
</head>

<body>

  <hello-shadow-dom></hello-shadow-dom>

  <button id="change"> 更改链接名称 </button>

  <script>
    class CustomElement extends HTMLElement {
      constructor() {
        super()
        this.shadowRootDom = this.attachShadow({ mode: 'closed' })  // open  |  closed
      }
      connectedCallback() {
        this.shadowRootDom.innerHTML = '<a href="#">My link</a>'
      }
    }
    customElements.define('hello-shadow-dom', CustomElement)


    const customEle = document.querySelector('hello-shadow-dom')
    console.log('打印 是否 能访问到 shadowRoot', customEle.shadowRoot)

    const changeBtn = document.getElementById('change')

    changeBtn.addEventListener('click', function () {
      if (customEle.shadowRoot) {
        customEle.shadowRoot.innerHTML = '链接'
      }


    })


  </script>
</body>

</html>