JavaScript组合模式学习要点

//定义组合对象var Folder = function (name) {this.name = name;this.parent = null;this.files = [];};Folder.prototype.add = function (file) {file.parent = this;if(this.files.indexOf(file) === -1){this.files.push(file);}else{console.log('/''+file.name+'/'已存在,添加失败');}};Folder.prototype.scan = function () {if(this.parent){console.log('开始扫描/''+this.parent.name+'/': '+this.name);}else{console.log('开始扫描根目录: '+this.name);}//关键在这里，调用所有它的叶对象的接口方法scan()for(var i = 0, file; file = this.files[i++];){file.scan();}};Folder.prototype.remove = function (file) {var n = this.files.indexOf(file);if(n === -1){console.log('无法删除: /''+file.name+'/'不存在:');}if(n >= 0){this.files.splice(n,1);console.log('成功删除:'+file.name);}};//定义叶对象var File = function (name) {this.name = name;this.parent = null;};File.prototype.add = function () {console.log('不能添加在文件下面');};File.prototype.scan = function () {console.log(this.parent.name+': '+this.name);};File.prototype.remove = function (file) {console.log('无法删除: /''+file.name+'/'不存在:');};//测试var folder = new Folder('目录');var folder1 = new Folder('学习质料');var folder2 = new Folder('javascript');var file1 = new File('Node.js');var file2 = new File('qq.jpg');folder.add(folder1);folder.add(folder1);folder.add(folder2);folder1.add(file1);folder2.add(file2);//'学习质料'添加成功//'学习质料'已存在,添加失败//'javascript'添加成功//'Node.js'添加成功//'qq.jpg'添加成功folder.remove(folder1);folder.remove(folder1);file1.remove(file1);//成功删除:学习质料//无法删除: '学习质料'不存在://无法删除: 'Node.js'不存在:folder.scan(); //这里相当于执行了一个宏命令//开始扫描根目录: 目录//开始扫描'目录': javascript//javascript: qq.jpg