JS 混合构造函数 和 动态原型

混合构造函数,  就是 原型模式+普通构造函数方式

构造函数 定义对象的非函数属性.

原型方式  定义 对象的函数属性(方法)

function Car(sColor,iDoors,iMpg) {

  this.color = sColor;

  this.doors = iDoors;

  this.mpg = iMpg;

  this.drivers = new Array("Mike","John");

}



Car.prototype.showColor = function() {

  alert(this.color);

};



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

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



oCar1.drivers.push("Bill");



alert(oCar1.drivers);    //输出 "Mike,John,Bill"

alert(oCar2.drivers);    //输出 "Mike,John"

下面说下动态原型:

function Car(sColor,iDoors,iMpg) {

  this.color = sColor;

  this.doors = iDoors;

  this.mpg = iMpg;

  this.drivers = new Array("Mike","John");

  

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

    Car.prototype.showColor = function() {

      alert(this.color);

    };

    

    Car._initialized = true;

  }

}

不管实例化多少个 car对象,那么 showColor函数 只初始化一次.