Web40.设计模式

构造函数模式

//constructor

function Person(name, age){
    this.name = name;
    this.age = age;
}
Person.prototype.sayName = function(){
    return this.name;
};
var student = new Person("fem", 30);

混合模式

//mixing
//混合原型
//一般在继承的时候用

//student继承person
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 = create(Person.prototype);


function create(parentObj){
    function F(){}
    F.prototype = parentObj;
    return new F();
}
Student.prototype.sayScore = function(){
    console.log(this.score);
}
var student = new Student("fem", 28, 99);

模块模式

//module


var Person = (function(){
    var name = 'ruoyu';
    function sayName(){
        console.log(name);
    }
    
    return {
        name: name,
        sayName: sayName
    }
})()

工厂模式

//factory
//每次创建一个新的引用

function createPerson(name){
    var person = {
        name: name,
        sayName: function(){
            console.log(this.name);
        }
    }
}
createPerson('fem');
createPerson('emmmmm');

单例模式

//singleton
//匿名函数 ==> lambda函数
//节约内存
//比如对话框

var People = (function(){
    var instance;
    function init(name){
        return {
            name:name
        };
    }
    return {
        createPeople: function(name){
            if (!instance){
                instance = init(name);
            }
            return instance;
        };
    }
}());
People.createPeople('fem')  //{name: 'fem'}
People.createPeople('emmm')  //{name: 'fem'}

发布订阅模式

//publish subscribe

var EventCenter = (function(){
    var events = {};   //存储所有的key value

    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);
        }
    }

    function off(name){
        delete events[name]
    }

    return {
        on: on,
        fire: fire,
        off: off  
    }
})();

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

Event.on('change', function(val){
 console.log('change...  now val is ' + val);  
});
Event.fire('change', '饥人谷');
Event.off('changer');

var Event = (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);
        }
    }  

    function off(name){
        delete events[name]
    }

    return {
        on: on,
        fire: fire,
        off: off
    }
})()