JS设计模式之命令模式

<style type="text/css">
.bnt{
 margin: 5px;
 border: 0;
 width: 70px;
 height: 35px;
 background: #6B78BF;
 color: white;
 font-size: 14px;
 cursor: pointer;
}
#textarea{
 margin: 5px;
 width: 400px;
 height: 200px;
 resize: none;
 color: #666;
 font-size: 14px;
 border: 2px solid #6B78BF;
}
</style>

<script type="text/javascript">
// 在页面中使用例：setCommand(btn, refreshMenuBarCommand );来发送命令
// setCommand 函数负责往按钮上面安装命令，预留好安装命令的接口
var setCommand = function( btn , command ){
 btn.onclick = function(){
 command.execute();
 }
}
 
// 编写点击按钮之后的具体行为：刷新菜单界面、增加子菜单和删除子菜单
var MenuBar = {
 refresh: function(){
 var cur_date = new Date();
 document.getElementById("textarea").value+=cur_date.toLocaleString()+" 刷新菜单目录\r"; }
}
var SubMenu = {
 add: function(){
 var cur_date = new Date();
 document.getElementById("textarea").value+=cur_date.toLocaleString()+" 新增菜单目录\r"; },
 del: function(){
 var cur_date = new Date();
 document.getElementById("textarea").value+=cur_date.toLocaleString()+" 删除子级菜单\r";}
} 
//封装行为在命令类中
var RefreshMenuBarCommand = function( receiver ){
 this.receiver = receiver;
 
}
RefreshMenuBarCommand.prototype.execute = function(){
 this.receiver.refresh();
}
var AddSubMenuCommand = function( receiver ){
 this.receiver = receiver;
}
AddSubMenuCommand.prototype.execute = function(){
 this.receiver.add();
}
var DelSubMenuCommand = function( receiver ){
 this.receiver =receiver
}
DelSubMenuCommand.prototype.execute = function(){
 this.receiver.del();
}
 
//命令接收者传入到 command 对象
var refreshMenuBarCommand = new RefreshMenuBarCommand( MenuBar );
var addSubMenuCommand = new AddSubMenuCommand( SubMenu );
var delSubMenuCommand = new DelSubMenuCommand( SubMenu );
 
window.onload = function(){
 //把 command 对象安装到 button 上面
 var btn1 = document.getElementById("button1");
 var button2 = document.getElementById("button2");
 var button3 = document.getElementById("button3");
 setCommand( btn1, refreshMenuBarCommand );
 setCommand( btn2, addSubMenuCommand );
 setCommand( btn3, delSubMenuCommand );
}
</script>