真实dom

    <ul id='list'>
        <li class='item'>Item 1</li>
        <li class='item'>Item 2</li>
        <li class='item'>Item 3</li>
    </ul>

虚拟dom

    let el = new Element('ul', { id: 'list' }, [
        new Element('li', { class: 'item' }, ['Item1']),
        new Element('li', { class: 'item' }, ['Item2']),
        new Element('li', { class: 'item' }, ['Item3']),
    ]);

构建连接类

    class Element {
        constructor(tagName, props, children) {
            this.tagName = tagName;
            this.props = props;
            this.children = children;
        }
        render() { //渲染，递归
            let el = document.createElement(this.tagName);
            let props = this.props;
            for (let propName in props) {
                let propValue = props[propName];
                el.setAttribute(propName, propValue);
            }
            let children = this.children || [];
            children.forEach((child) => {
                var childEl;
                if (child instanceof Element) {
                    childEl = child.render();
                } else {
                    childEl = document.createTextNode(child);
                }
                el.appendChild(childEl);
            });
            return el;
        }
    }

    /**虚拟dom描述真实dom
    <ul id='list'>
        <li class='item'>Item 1</li>
        <li class='item'>Item 2</li>
        <li class='item'>Item 3</li>
    </ul>
    **/
    let el = new Element('ul', { id: 'list' }, [
        new Element('li', { class: 'item' }, ['Item1']),
        new Element('li', { class: 'item' }, ['Item2']),
        new Element('li', { class: 'item' }, ['Item3']),
    ]);
    let ul = el.render();
    document.body.appendChild(ul);