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

• ** 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