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Showing content from https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Map/keys below:

Map.prototype.keys() - JavaScript | MDN

Map.prototype.keys()

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Map 实例的 keys() 方法返回一个新的 map 迭代器对象,该对象包含了此 map 中每个元素的键,按插入顺序排列。

尝试一下
const map1 = new Map();

map1.set("0", "foo");
map1.set(1, "bar");

const iterator1 = map1.keys();

console.log(iterator1.next().value);
// Expected output: "0"

console.log(iterator1.next().value);
// Expected output: 1
语法 参数

无。

返回值

一个新的可迭代迭代器对象。

示例 使用 keys()
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); // {}
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