Map.prototype.keys()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

Map 实例的 keys() 方法返回一个新的 地图迭代器 对象，其中包含此映射中按插入顺序排列的每个元素的键。

¥The keys() method of Map instances returns a new map iterator object that contains the keys for each element in this map in insertion order.

Try it

语法

¥Syntax

js
keys()

参数

¥Parameters

没有任何。

¥None.

返回值

¥Return value

新的 可迭代的迭代器对象。

¥A new iterable iterator object.

示例

¥Examples

使用键()

¥Using keys()

js
const myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

const mapIter = myMap.keys();

console.log(mapIter.next().value); // "0"
console.log(mapIter.next().value); // 1
console.log(mapIter.next().value); // {}

规范

Specification
ECMAScript Language Specification
# sec-map.prototype.keys

¥Specifications

浏览器兼容性

BCD tables only load in the browser

¥Browser compatibility

也可以看看

¥See also