JS map keys()
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。
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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 |