第3章对象基础

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<head>

<title>定义类和对象</title>

</head>

<body>

1.工厂方式：<br />

//定义

function createCar(color, doors, mpg) {

var oCar = new Object();

oCar.color = color;

oCar.doors = doors;

oCar.mpg = mpg;

oCar.showColor = function () { alert("1.工厂方式：" + this.color); };

return oCar;

}

//调用

var car = createCar("red", 4, 23);

car.showColor();

</script>

2.构造函数方式：<br />

//定义

function Car(color, doors, mpg) {

this.color = color;

this.doors = doors;

this.mpg = mpg;

this.showColor = function () { alert("2.构造函数方式：" + this.color); };

}

//调用

var car2 = new Car("blue", 4, 23);

car2.showColor();

</script>

3.原型方式：<br />

//定义

function pCar() { }

pCar.prototype.color = "green";

pCar.prototype.doors = 4;

pCar.prototype.mpg = 23;

pCar.prototype.showColor = function () { alert("3.原型方式测试：" + this.color); };

//调用

var car3 = new pCar();

alert(car3 instanceof pCar); //允许用instanceof运算符检查给定变量指向的对象的类型。

car3.showColor();

</script>

4.混合构造函数/原型方式：<br />

//定义

//构造函数定义属性

function sCar(color, doors, mpg) {

this.color = color;

this.doors = doors;

this.mpg = mpg;

}

//原型方式定义函数

sCar.prototype.showColor = function () { alert("4.混合构造函数/原型方式测试：" + this.color); };

//调用

var car4 = new sCar("yellow", 4, 23);

car4.showColor();

</script>

5.动态原型方式：<br />

//定义

function dCar(color, doors, mpg) {

this.color = color;

this.doors = doors;

this.mpg = mpg;

//将对象的方法放到对象内部，更符合面向对象思想

if (typeof dCar._initialized == "undefined") {

dCar.prototype.showColor = function () { alert("5.动态原型方式测试：" + this.color); };

dCar._initialized = true;

}

//调用

var car5 = new dCar("black", 4, 23);

car5.showColor();

</script>

</body>

</html>

第3章 对象基础

第3章对象基础