通过prototype属性建立面向对象的JavaScript

function Car(){}
Car.prototype.wheelCount = 4;
Car.prototype.color = "not set";
Car.prototype.go = function() {
 return "Car.go";
}
Car.prototype.stop = function() {
 return "stop";
}

function SportsCar(){}
SportsCar.prototype = new Car();
SportsCar.prototype.color = "green";
SportsCar.prototype.name = "Sports Car";
SportsCar.prototype.go=function(){
 return "SportsCar go";
}
SportsCar.prototype.contest= function(){
 return "contest";
}

function test() {
 var sportsCar = new SportsCar();
 alert(sportsCar.wheelCount);//4
 alert(sportsCar.color);//green
 alert(sportsCar.name);//Sports Car
 alert(sportsCar.go());//SportsCar go
 alert(sportsCar.stop());//stop
 alert(sportsCar.contest());//contest
}