@@iterator
属性和 Array.prototype.values()
属性的初始值是同一个函数对象。
语法
arr[Symbol.iterator]()
返回值
数组的 iterator 方法,默认情况下,与 values()
函数。
示例
使用 for...of
循环进行迭代
var arr = ['a', 'b', 'c', 'd', 'e']; var eArr = arr[Symbol.iterator](); var eArr = arr[Symbol.iterator](); // 浏览器必须支持 for...of 循环 for (let letter of eArr) { console.log(letter); }
另一种迭代方式
var arr = ['a', 'b', 'c', 'd', 'e']; var eArr = arr[Symbol.iterator](); console.log(eArr.next().value); // a console.log(eArr.next().value); // b console.log(eArr.next().value); // c console.log(eArr.next().value); // d console.log(eArr.next().value); // e
Use Case for brace notation
The use case for this syntax over using the dot notation (Array.prototype.values()
) is in a case where you don't know what object is going to be ahead of time. If you have a function that takes an iterator and then iterate over the value, but don't know if that Object is going to have a [Iterable].prototype.values method. This could be a built-in object like String object or a custom object.
function logIterable(it) { var iterator = it[Symbol.iterator](); // 浏览器必须支持 for...of 循环 for (let letter of iterator) { console.log(letter); } } // Array logIterable(['a', 'b', 'c']); // a // b // c // string logIterable('abc'); // a // b // c
规范
规范名称 | 规范状态 | 备注 |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) Array.prototype[@@iterator]() |
Standard | 首次定义 |
ECMAScript Latest Draft (ECMA-262) Array.prototype[@@iterator]() |
Draft |
浏览器兼容性
The compatibility table in 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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
@@iterator |
Chrome Full support 38 | Edge Full support 12 | Firefox Full support 36
|
IE No support No | Opera Full support 25 | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support 38 | Firefox Android Full support 36
|
Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes | nodejs Full support 0.12 |
Legend
- Full support
- Full support
- No support
- No support
- See implementation notes.
- See implementation notes.
- Uses a non-standard name.
- Uses a non-standard name.