keys() 方法返回一个包含数组中每个索引键的Array Iterator对象。
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语法
arr.keys()
返回值
一个新的 Array 迭代器对象。
示例
索引迭代器会包含那些没有对应元素的索引
var arr = ["a", , "c"];
var sparseKeys = Object.keys(arr);
var denseKeys = [...arr.keys()];
console.log(sparseKeys); // ['0', '2']
console.log(denseKeys); // [0, 1, 2]
规范
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 2015 (6th Edition, ECMA-262) Array.prototype.keys |
Standard | Initial definition. |
| ECMAScript (ECMA-262) Array.prototype.keys |
Living Standard |
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