<script language="javascript" type="text/javascript">
function Cat(){
}

var cat1 = new Cat();//創建類實例

cat1.name = "小狗";
cat1.age = 4;
cat1.color="白色";
document.write(cat1.name);

document.writeln(cat1.constructor);//實例化后對象，是對象
document.writeln(typeof(cat1)+"<hr />");

document.writeln(Cat.constructor);//原型對象本身也是對象
document.writeln(typeof Cat+"<hr />");

var b="hello";//字符串也是對象
document.writeln(b.constructor);//輸出它的構造函數
document.writeln(typeof b+"<hr />");

var c=123;//數值也是對象
document.writeln(c.constructor);
document.writeln(typeof c+"<hr />");
</script>

if(cat1 instanceof Cat){//與php的判斷方法相同
 window.alert("ok");
}