Array.prototype.keys() - JavaScript 编辑

 keys() 方法返回一个包含数组中每个索引键的Array Iterator对象。

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

浏览器兼容性

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相关链接

• Array.prototype.values()
• Array.prototype.entries()
• Iteration protocols