常见的设计模式

构造函数模式
例子：

function Person(name,age){
    this.name = name
    this.age = age
}
Person.prototype.sayName = function(){
    return this.name
}
var student = new Person('小明',20)
console.log(student)

混合模式
最典型的应用就是原型的继承
例子

function Person(name, age) {
    this.name = name
    this.age = age
}
Person.prototype.sayName = function() {
    return this.name
}

function Student(name, age, score) {
    Person.call(this, name, age)
    this.score = score
}

function create(parentObj) {
    function F() {}
    F.prototype = parentObj
    return new F()
}

//Student.prototype = Object.create(Person.prototype) 在chrome等现代浏览器上使用

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

var student = new Student('小明', 20, 100)
console.log(student)

模块模式
例子

var Person = (function(){
    var name = '小dong'
    

    return{
       changeName:function (newName){
        name = newName
    },
       sayName:function(){
           console.log(name)
       } 
    }
})()
Person.changeName('xiaoming')
Person.sayName()

单例模式
例子：

var Person = (function(){
    var instance
    function init(){
        //init可以自由定义

        var name = '小明'
        return{
            sayName:function(){
                console.log(name)
            }
        }
    }
    return{
        createPerson:function(){
            if(!instance){
                instance = init()
            }
            return instance
        }
    }
})()

var obj1 = Person.createPerson()
var obj2 = Person.createPerson()
//两个obj都指向了同一个对象

发布订阅模式

var EventCenter = (function(){
    var events = {}
    /*
        {
            
        }
    */

    function subscribe (event,handler){
        events[event] = events[event] || []
        events[event].push({
            handler:handler
        })
    }

    function publish(event,arguments){
        if(!events[event]){
            return
        }
        for(var i=0;i<events[event].length;i++){
            events[event][i].handler(arguments)
        }
    }

    return {
        subscribe:subscribe,
        publish:publish
    }
})()

2.

var EventCenter = (function(){
    var events = {}
    /*
        {
            
        }
    */

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

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