把字符串转换为数组 split()

1、split("")与split(" ")的区别：

window.onload=function(){
            var arr="abc";
            console.log(arr);//abc
            var a=arr.split(" ");
            console.log(a);//["abc"]
            var b=arr.split("");//console.log(a);
            console.log(b);//["a", "b", "c"]
            console.log(typeof(a));//object
        }window.onloa