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。
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
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
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out
https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
keys |
Chrome Full support 38 | Edge Full support 12 | Firefox Full support 20 | IE No support No | Opera Full support 25 | Safari Full support 8 | WebView Android Full support 38 | Chrome Android Full support 38 | Firefox Android Full support 20 | Opera Android Full support 25 | Safari iOS Full support 8 | Samsung Internet Android Full support 3.0 | nodejs Full support 0.12 |
Legend
- Full support
- Full support
- No support
- No support