function Machine(ecode, horsepower) {
  this.ecode = ecode;
  this.horsepower = horsepower;
}

function showme() {
  alert(this.name + " " + this.ecode + " " + this.horsepower);
}

var machine = new Machine("code1", 15);
machine.name = "machine1";
machine.showme = showme;
machine.showme();

//機(jī)器
function Machine(ecode, horsepower) {
  this.ecode = ecode;
  this.horsepower = horsepower;
}
//特別注意這一句，Machine.prototype是第一次初始化的時候就初始化好的，
//當(dāng)調(diào)用Machine作為構(gòu)造函數(shù)的時候，engine的值不會再改變
Machine.prototype.engine = this.ecode + " " + this.horsepower;
Machine.prototype.showme = function () { alert(this.name + " " + this.ecode + " " + this.horsepower); }

var machine = new Machine("code1", 15);
machine.name = "machine1";
machine.showme(); //輸出machine1 code1 15。

//小汽車
function Car(name, ecode, horsepower) {
  this.name = name;
  //調(diào)用父類的構(gòu)造函數(shù)，使得Car的對象有ecode、horsepower屬性
  Machine.call(this, ecode, horsepower);
}
//Car的原型指向Machine，使Car對象有Machine原型的任意屬性和方法，比如showme
Car.prototype = new Machine();

//新建一個類Car的對象。
var xiali = new Car("xiali", "aaa", 15);
alert(xiali.engine);
xiali.showme();