关于js的for in的一个问题

Question

var xvar mycars = new Array()mycars[0] = "Saab"mycars[1] = "Volvo"mycars[2] = "BMW"for (x in mycars){document.write(mycars[x] + "<br />")}为什么这里X的值默认就成了0,1,2啊

Answer 1

x 不是属性key么，你这里的mycars对象里的key不就是0,1,2?