如何在HTML的影子DOM中添加子级？ 您可以自己移动它：或者您使用shadowDOM插槽

问题描述

例如，我希望能够用HTML编写此代码：

<my-container>
  Some text.
</my-container>

JS：

class MyContainer extends HTMLElement {
  constructor() {
    super()
    const shadow = this.attachShadow({mode: 'open'})
    const p = document.createElement('p')
    shadow.appendChild(p)
  }
}

customElements.define('my-container',MyContainer)

我最终得到的结果（虽然并不意外）：

<my-container>
  <p></p>
  Some text.
</my-container>

我想要什么：

<my-container>
  <p>Some text.</p>
</my-container>

解决方法

带有shadowDOM 的自定义元素中的HTML保留在 lightDOM

中（不可见）

您可以自己移动它：

<my-element>
  Hello World,I came from lightDOM
</my-element>

<script>
  customElements.define("my-element",class extends HTMLElement {
    constructor() {
      super().attachShadow({
        mode: 'open'
      }); // sets and returns thi.shadowRoot for free
      this.wrapper = this.shadowRoot.appendChild(document.createElement('H1'));
      this.wrapper.innerHTML = "please click me";
    }
    connectedCallback() {
      this.onclick = () => this.wrapper.innerHTML = this.innerHTML;
    }
  });
</script>

或者您使用shadowDOM插槽

<style>
 my-element{
  color:green;
 }
</style>
<my-element>
  Hello World,I am REFLECTED from lightDOM
</my-element>

<script>
  customElements.define("my-element",class extends HTMLElement {
    constructor() {
      super().attachShadow({
        mode: 'open'
      }); // sets and returns thi.shadowRoot for free
      this.wrapper = this.shadowRoot.appendChild(document.createElement('H1'));
      this.wrapper.innerHTML = "<slot></slot";
    }
    connectedCallback() {
    }
  });
</script>

请注意内容的样式！

text / html 保留 in lightDOM，它被反射 IN shadowDOM

请阅读：::slotted CSS selector for nested children in shadowDOM slot