Javascript Class

做个记录，javascript 如何创建类？

有早期的，有原型的，有构造函数的

// early javascript object

var o = {};

o.color = 'red';

o.showColor = function () {

    alert(this.color);

};

o.showColor();



// prototype

function Car() {}

Car.prototype.color = 'red';

Car.prototype.doors = 4;

Car.prototype.mpg = 23;

Car.prototype.drivers = new Array('Mike', 'Sue');

Car.prototype.showColor = function () {

    alert(this.color);

};

var oCar1 = new Car();

var oCar2 = new Car();

oCar1.drivers.push('Matt');

alert(oCar1.drivers); //outputs “Mike,Sue,Matt”

alert(oCar2.drivers); //outputs “Mike,Sue,Matt”



// prototype && constructor

function Car(sColor, iDoors, iMpg) {

    this.color = sColor;

    this.doors = iDoors;

    this.mpg = iMpg;

    this.drivers = new Array('Mike', 'Sue');

}

Car.prototype.showColor = function () {

    alert(this.color);

};

var oCar1 = new Car('red', 4, 23);

var oCar2 = new Car('blue', 3, 25);

oCar1.drivers.push('Matt');

alert(oCar1.drivers); //outputs “Mike,Sue,Matt”

alert(oCar2.drivers); //outputs “Mike,Sue”



// Dynamic prototype method

function Car(sColor, iDoors, iMpg) {

    this.color = sColor;

    this.doors = iDoors;

    this.mpg = iMpg;

    this.drivers = new Array('Mike', 'Sue');

    

    if (typeof Car._initialized == 'undefined') {

        Car.prototype.showColor = function () {

            alert(this.color);

        };

        Car._initialized = true;

    }

}