JavaScript定义类和对象

1. //方法一
2. functionCar(sColor,iDoors,iMpg){
3. this.color=sColor;
4. this.doors=iDoors;
5. this.mpg=iMpg;
6. this.drivers=newArray(“Mike”,“Sue”);
7. }
8. Car.prototype.showColor=function(){
9. alert(this.color);
10. };
11. varoCar1=newCar(“red”,4,23);
12. varoCar2=newCar(“blue”,3,25);
13. oCar1.drivers.push(“Matt”);
14. alert(oCar1.drivers);//outputs“Mike,Sue,Matt”
15. alert(oCar2.drivers);//outputs“Mike,Sue”
17. //方法二
18. functionCar(sColor,iDoors,iMpg){
19. this.color=sColor;
20. this.doors=iDoors;
21. this.mpg=iMpg;
22. this.drivers=newArray(“Mike”,“Sue”);
23. if(typeofCar._initialized==“undefined”){
24. Car.prototype.showColor=function(){
25. alert(this.color);
26. };
27. Car._initialized=true;
28. }
29. }

使用了prototype后，可以用instanceof 来判断这个对象是否属于一个类的实例。比如：oCar1 instanceof Car