Map.prototype.keys() - JavaScript 编辑

keys() 返回一个引用的 Iterator 对象。它包含按照顺序插入 Map 对象中每个元素的key值。

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语法

myMap.keys()

返回值

一个存在引用关系的 Map iterator 对象.

例子

使用 keys()

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

var mapIter = myMap.keys();

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

规范

规范	状态	备注
ECMAScript 2015 (6th Edition, ECMA-262) Map.prototype.keys	Standard	Initial definition.
ECMAScript (ECMA-262) Map.prototype.keys	Living Standard

浏览器兼容性

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参见

• Map.prototype.entries()
• Map.prototype.values()