设计模式

** 写出 构造函数模式、混合模式、模块模式、工厂模式、单例模式、发布订阅模式的范例。**

单例模式

 var People = (function(){
     var instance;
     function init(name){
 //定义私有变量和方法
 
      return {
     //定义共有变量和方法(可以访问私有变量和方法)
     sayName:function(){
         console.log(name);
     }
 };
 }

 return {
     getInstance:function(name){
         if(!instance){
             instance = init(name);
         }
         return instance;
     }
 }
 }());

  var p1 = People.getInstance("jack");
  var p2 = People.getInstance("keanu");
  p1 == p2; //true
 //console.log(p1 == p2);

构造函数模式

 function Person(name) {
     this.name = name;
 }
 Person.prototype = {
     say: function () {
         console.log(this.name)
     }
 }
 var p2 = new Person('Rick');

混合模式 -继承

 var Person = function (name,age) {
     this.name = name;
     this.age = age;
 }
 Person.prototype = {
 sayName: function () {
     console.log(this.name)
    }
  }
 var Student = function (name,age,score) {
      Person.call(this,name,age);
     this.score = score;
 }

 //Student.prototype = Object.create(Person.prototype)
  Student.prototype = create(Person.prototype)
  function create(fn) {
       function F(){};
       F.prototype = fn;
  return new F()
  }

   Student.prototype.constructor = Student;
   Student.prototype.sayScore = function(){
        console.log(this.score);
   }

 var student = new Student('Nick',23,90)

模块模式

 var Person = (function(){
 function changeName(name) {
     this.name = name;
 }
 function sayName() {
     console.log(this.name)
 }
 return{
     change: changeName,
     say: sayName
 }
 })()

工厂模式

 var People=function(name,age){
     return {
         name:name,
         age:age,
         sayName:function(){
             console.log('my name is '+this.name);
         },
         setAge:function(age){
             this.age=age;  
         },
         getAge:function(){
             console.log(this.age);
         }
     }
 }
 var p3=People('jack',24);
 p3.sayName();
 p3.getAge();
 p3.setAge(27);
 p3.getAge();

发布订阅模式

 <script type="text/javascript">
  var EventCenter = (function(){
       var events = {};

 function on(evt, handler){
     events[evt] = events[evt] || [];
     events[evt].push({
         handler: handler
 });
 }

 function fire(evt, args){
     if(!events[evt]){
 return;
 }
 for(var i=0; i<events[evt].length; i++){
     events[evt][i].handler(args);
 }
 }
 return {
     on: on,
     fire: fire
 }
 })();

 EventCenter.on('my_event', function(data){
       console.log('my_event ...');
 });

 EventCenter.fire('my_event');
 </script>

** 使用发布订阅模式写一个事件管理器，可以实现如下方式调用**

var Event=(function(){
var events={};
function on(evt,handler){
    events[evt]=events[evt] || [];
    events[evt].push({
        handler:handler
  })
}
function fire(evt,arg){
  if(!events[evt]){
      return 
  }
  for(var i=0;i<events[evt].length;i++){
      events[evt][i].handler(arg)
  }
}
function off(evt){
  delete events[evt];
}
return {
  on:on,
  fire:fire,
  off:off
}
}());
Event.on('change', function(val){
     console.log('change...  now val is ' + val);  
});
Event.fire('change', '饥人谷'); //change...  now val is 饥人谷
Event.off('change');