tools/virtual-dom.html at master · supfn/tools · GitHub

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<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>VirtualDom</title>
</head>

<body>
  <script>

    function createElement(vnode) {
      let tagName = vnode.tagName;
      let props = vnode.props || {};
      let children = vnode.children || [];
      if (typeof tagName !== 'string' || tagName.length === 0) {
        return null
      }
      let el = document.createElement(tagName);
      for (let propName in props) {
        let propValue = props[propName];
        el.setAttribute(propName, propValue);
      }
      children.forEach(child => {
        let childEl = (child instanceof VNode) ? createElement(child) : document.createTextNode(child);
        el.appendChild(childEl);
      });
      return el;
    }

    function updateChildren(vnode, newVnode) {
      let children = vnode.children || [];
      let newChildren = newVnode.children || [];
      // 遍历现有的children
      children.forEach((childVnode, index) => {
        let newChildVnode = newChildren[index]
        // 两者tag一样
        if (childVnode.tag === newChildVnode.tag) {
          // 深层次对比，递归
          updateChildren(childVnode, newChildVnode)
        } else {
          // 两者tag不一样
          replaceNode(childVnode, newChildVnode)
        }
      })
    }

    class VNode {
      /**
       * @param {String}  tagName     标签名
       * @param {Object}  props       元素的属性对象
       * @param {Array}   children    子节点
       */
      constructor(tagName, props = {}, children = []) {
        if (typeof tagName !== 'string' || tagName.length === 0) {
          throw new Error('Please input correct tag name');
        }
        this.tagName = tagName;
        this.props = props;
        this.children = children;
      }
      render() {
        return createElement(this);
      };
    }

    let ul = new VNode('ul', { id: 'list' }, [
      new VNode('li', { class: 'item' }, ['item1']),
      new VNode('li', { class: 'item' }, ['item2']),
      new VNode('li', { class: 'item' }, ['item3']),
    ]);
    let ulElem = ul.render();
    document.body.appendChild(ulElem);

  </script>
</body>

</html>