Object.keys()详解

Object.keys()：遍历对象的所有属性，该方法返回一个数组，数组内容就是对象的所有键名。

传入对象，返回属性名

1var obj= {'a':'meng','b':'lin'}
2console.log(Object.keys(obj));
3// ['a','b']
4var obj={ 100: "a", 2: "b", 7: "c"};
5console.log(Object.keys(obj1)); 
6// console: ["2", "7", "100"]
7var obj2 = Object.create({}, { getFoo : { value : function () { return this.foo } } });
8obj2.foo = 1;
9console.log(Object.keys(obj2)); 
10// console: ["foo"]

传入字符串，返回索引

1var str = 'ab1234';
2console.log(Object.keys(str));  //[0,1,2,3,4,5]

获取字符串中的某一个值

1var str = 'ab1234';
2console.log(Object.keys(str));  //[0,1,2,3,4,5]
3 
4Object.keys(str).map(function (index) {
5  console.log(str[index]);
6});
7//a,b,1,2,3,4

数组 返回索引

1 var arr = ["a", "b", "c"];
2    console.log(Object.keys(arr)); // console: ["0", "1", "2"]