1.9 KiB
1.9 KiB
title | localeTitle |
---|---|
Object Keys | 对象键 |
Object.keys()
方法返回给定对象自己的可枚举属性的数组,其顺序与for...in
循环提供的顺序相同(不同之处在于for-in
循环枚举原型链中的属性为好)。
句法
Object.keys(obj)
参数
OBJ
要返回其可枚举自身属性的对象。
描述
Object.keys()
返回一个数组,其元素是与直接在对象上找到的可枚举属性相对应的字符串。属性的顺序与通过手动循环对象的属性给出的顺序相同。
例子
var arr = ['a', 'b', 'c'];
console.log(Object.keys(arr)); // console: ['0', '1', '2']
// array like object
var obj = { 0: 'a', 1: 'b', 2: 'c' };
console.log(Object.keys(obj)); // console: ['0', '1', '2']
// array like object with random key ordering
var an_obj = { 100: 'a', 2: 'b', 7: 'c' };
console.log(Object.keys(an_obj)); // console: ['2', '7', '100']
// getFoo is property which isn't enumerable
var my_obj = Object.create({}, { getFoo: { value: function() { return this.foo; } } });
my_obj.foo = 1;
console.log(Object.keys(my_obj)); // console: ['foo']
// Create a constructor function.
function Pasta(grain, width, shape) {
this.grain = grain;
this.width = width;
this.shape = shape;
// Define a method.
this.toString = function () {
return (this.grain + ", " + this.width + ", " + this.shape);
}
}
// Create an object.
var spaghetti = new Pasta("wheat", 0.2, "circle");
// Put the enumerable properties and methods of the object in an array.
var arr = Object.keys(spaghetti);
document.write (arr);
// Output:
// grain,width,shape,toString