JavaScript 定义类

构造函数定义

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;
    }
}

var car1 = new Car("red", 4, 23);
var car2 = new Car("blue", 3, 25);

car1.drivers.push("matt");
alert(car1.drivers); // outputs "mike,sue,matt"
alert(car2.drivers); // outputs "mike,sue,matt"

console.log(car1 instanceof Car); // true

该示例展示了 JavaScript 中通过构造函数创建对象实例的基本方式，包含属性初始化、原型方法懒加载及类型检查。