了解javascript对象文字内的键名的方法

Question

declare a javascript object literal 声明一个javascript对象文字

var objA = {'keyA':'valA'}

in the console 在控制台中

objA
> Object {keyA: "valA"}

the object is not an array 该对象不是数组

objA[0]
> undefined

the only way I know to get key names is to cicle on the object 我知道获取键名的唯一方法是在对象上单击cicle

for (x in objA) {
    console.log(x);
}
> keyA

Do you know any other ways to get key names from object? 您是否知道从对象获取键名的其他方法？

Answer 1

You can use Object.keys like this 您可以像这样使用Object.keys

var objA = {'keyA':'valA'};
console.log(Object.keys(objA));

var objA = {'keyA':'valA'}, keys = [];
for (var key in objA) {
    keys.push(key);
}

Answer 2

You could use Object.keys() do this: 您可以使用Object.keys()执行此操作：

var objA = { 'keyA': 'valA', 'foo': 'bar' };
Object.keys( objA ); // [ 'keyA', 'foo' ]

Note that this is not supported on all browsers yet - but it is on the modern versions of the popular ones. 请注意，目前尚不是所有浏览器都支持此功能-但在流行浏览器的现代版本中却支持。

Answer 3

var keys = Object.keys(objA);

Answer 4

Object.keys function is available in newer browsers: 在较新的浏览器中可以使用Object.keys函数：

var keys = Object.keys(objA);