14.组合模式

var News = function() {
        this.children = []
        this.element = null
    }
    News.prototype = {
        init: function() {
            throw new Error('initinit')
        },
        add: function() {
            throw new Error('addadaddadad')
        },
        getElement: function() {
            throw new Error('getelement')
        } 
    }
    var container = function(id, parent) {
        News.call(this)
        this.id = id
        this.parent = parent
        this.init()
    }
    container.prototype = new News()
    container.prototype.init = function() {
        this.element = document.createElement('ul')
        this.element.id = this.id
        this.element.className = 'newContainer'
    }
    container.prototype.add = function(child) {
        this.children.push(child)
        this.element.appendChild(child.getElement()) 
        return this                                                                    
    }
    container.prototype.getElement = function() {
        return this.element
    }
    container.prototype.show = function() {
        this.parent.appendChild(this.element)
    }
    var Item = function(className) {
        News.call(this)
        this.className = className
        this.init()
    }
    Item.prototype = new News()
    Item.prototype.init = function() {
        this.element = document.createElement('li')
        this.element.className = this.className
    }
    Item.prototype.add = function(child) {
        this.children.push(child)
        this.element.appendChild(child.getElement())
        return this
    }
    Item.prototype.getElement = function() {
        return this.element
    }
    var new1 = new container('news', document.body)
    new1.add(new Item('normal'))