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

语法

myMap.keys()

返回值

一个新的 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 Latest Draft (ECMA-262)
Map.prototype.keys
Draft

浏览器兼容性

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
Basic supportChrome Full support 38Edge Full support 12Firefox Full support 20IE No support NoOpera Full support 25Safari Full support 8WebView Android Full support 38Chrome Android Full support 38Edge Mobile Full support 12Firefox Android Full support 20Opera Android Full support 25Safari iOS Full support 8Samsung Internet Android Full support Yesnodejs Full support 0.12

Legend

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参见

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