velement.js

var util = require('./util');
//虚拟dom
var VElement = function(tagName, props, children) {
    //保证只能通过如下方式调用：new VElement
    if (!(this instanceof VElement)) {
        return new VElement(tagName, props, children);
    }

    //可以通过只传递tagName和children参数
    if (util.isArray(props)) {
        children = props;
        props = {};
    }

    //设置虚拟dom的相关属性
    this.tagName = tagName;
    this.props = props || {};
    this.children = children || [];
    this.key = props ? props.key : void 666;
    var count = 0;
    util.each(this.children, function(child, i) {
        if (child instanceof VElement) {
            count += child.count;
        } else {
            children[i] = '' + child;
        }
        count++;
    });
    this.count = count;
}

//根据虚拟dom创建真实dom
VElement.prototype.render = function() {
    //创建标签
    var el = document.createElement(this.tagName);
    //设置标签的属性
    var props = this.props;
    for (var propName in props) {
        var propValue = props[propName]
        util.setAttr(el, propName, propValue);
    }

    //一次创建子节点的标签
    util.each(this.children, function(child) {
        //如果子节点仍然为velement，则递归的创建子节点，否则直接创建文本类型节点
        var childEl = (child instanceof VElement) ? child.render() : document.createTextNode(child);
        el.appendChild(childEl);
    });

    return el;
}

module.exports = VElement;