Object.keys方法之详解
在实际开发中，我们有时需要知道对象的所有属性，原生js给我们提供了一个很好的方法：Object.keys()，该方法返回一个数组,其中这个数组的内容就是这个对象的所有键值
传入对象，返回属性名
var obj = {'a':'123','b':'345'};
console.log(Object.keys(obj)); //['a','b']
var obj1 = { 100: "a", 2: "b", 7: "c"};
console.log(Object.keys(obj1)); // console: ["2", "7", "100"]
var obj2 = Object.create({}, { getFoo : { value : function () { return this.foo } } });
obj2.foo = 1;
console.log(Object.keys(obj2)); // console: ["foo"]
传入字符串，返回索引 var str = 'ab1234';
console.log(Object.keys(str)); //[0,1,2,3,4,5]
如果我们想要获取字符串中的某一个值,那么我们就可以通过下面的方法获取: var str = 'ab1234';
console.log(Object.keys(str)); //[0,1,2,3,4,5]
Object.keys(str).map(function (index) {
console.log(str[index]);
});获取的结果如下面所示: [ '0', '1', '2', '3', '4', '5' ]
a
b
1
2
3
4我们可以进行自己的处理 构造函数 返回空数组或者属性名 function Pasta(name, age, gender) {
this.name = name;
this.age = age;
this.gender = gender;
this.toString = function () {
return (this.name + ", " + this.age + ", " + this.gender);
}
}
console.log(Object.keys(Pasta)); //console: []
var spaghetti = new Pasta("Tom", 20, "male");
console.log(Object.keys(spaghetti)); //console: ["name", "age", "gender", "toString"]数组 返回索引 var arr = ["a", "b", "c"];
console.log(Object.keys(arr)); // console: ["0", "1", "2"]
Notes
In ES5, if the argument to this method is not an object (a primitive), then it will cause a TypeError. In ES6, a non-object argument will be coerced to an object.
Object
.keys("foo");
Object
.keys("foo");
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