javascript 继承

1. 对象冒充

function ClassA(sColor)
    {
        this.color = sColor;
        this.sayColor = function ()
        {
            console.log(this.color);
        }
    }


    function ClassB(sColor, sName)
    {
        this.newMethod = ClassA;
        this.newMethod(sColor);
        delete this.newMethod;


        this.name = sName;
        this.sayName = function() 
        {
            console.log(this.name);
        }
    }

 

2. call()
     

function ClassB(sColor, sName)
    {
        ClassA.call(this, sColor);


        this.name = sName;
        this.sayName = function() 
        {
            console.log(this.name);
        }
    }

 

3. apply()
     

function ClassB(sColor, sName)
    {
        //ClassA.apply(this, new Array(sColor));
        ClassA.apply(this, arguments);


        this.name = sName;
        this.sayName = function() 
        {
            console.log(this.name);
        }
    }

 

4. 原型链
     

function ClassA()
    {}
    ClassA.prototype.color = 'red';
    ClassA.prototype.sayColor = function()
    {
        console.log(this.color);
    }


    function ClassB()
    {}
    ClassB.prototype = new ClassA();
    ClassB.prototype.name = '';
    ClassB.prototype.sayName = function()
    {
        console.log(this.name);
    }


    //instanceof
    var obj = new ClassB();
    console.log(obj instanceof ClassA); //outputs 'true'
    console.log(obj instanceof ClassB); //outputs 'true'

 

5. 混合方式
     

function ClassA(sColor)
    {
        this.color = sColor;
    }


    ClassA.prototype.sayColor = function ()
    {
        console.log(this.color);
    }


    function ClassB(sColor, sName)
    {
        ClassA.call(this, sColor);
        this.name = sName;
    }


    ClassB.prototype = new ClassA();


    ClassB.prototype.sayName = function()
    {
        console.log(this.name);
    }


    //test
    var objA = new ClassA('red');
    var objB = new ClassB('blue', 'Nicholas');
    objA.sayColor();
    objB.sayColor();
    objB.sayName();