var mycars=new Array("Saab","Volvo","BMW")
console.info(typeof mycars);//object
console.info(mycars);//["Saab", "Volvo", "BMW"]
var mycars=new Array("Saab","Volvo","BMW")
console.info(typeof mycars);//object
console.info(mycars);//["Saab", "Volvo", "BMW"]
ECMAScript中规定所有引用类型都是Object的实例,所以用typeof返回的是Object
可以用constructor instanceof Array 返回true