Symbol.asyncIterator
符号指定了一个对象的默认异步迭代器。如果一个对象设置了这个属性,它就是异步可迭代对象,可用于for await...of
循环。
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描述
Symbol.asyncIterator
是一个用于访问对象的@@asyncIterator
方法的内建符号。一个异步可迭代对象必须要有Symbol.asyncIterator
属性。
Symbol.asyncIterator 属性的属性特性: |
|
---|---|
writable | false |
enumerable | false |
configurable | false |
示例
自定义异步可迭代对象
你可以通过设置[Symbol.asyncIterator]
属性来自定义异步可迭代对象。
const myAsyncIterable = new Object(); myAsyncIterable[Symbol.asyncIterator] = async function*() { yield "hello"; yield "async"; yield "iteration!"; }; (async () => { for await (const x of myAsyncIterable) { console.log(x); // expected output: // "hello" // "async" // "iteration!" } })();
内建异步可迭代对象
目前没有默认设定了[Symbol.asyncIterator]
属性的JavaScript内建的对象。不过,WHATWG(网页超文本应用技术工作小组)Streams会被设定为第一批异步可迭代对象,[Symbol.asyncIterator]
最近已在设计规范中落地。
规范
标准 | 状态 | 注释 |
---|---|---|
ECMAScript 2018 (ECMA-262) Symbol.asyncIterator |
Standard |
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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
asyncIterator |
Chrome Full support 63 | Edge No support No | Firefox Full support 57 | IE No support No | Opera Full support 50 | Safari Full support 11.1 | WebView Android Full support 63 | Chrome Android Full support 63 | Firefox Android No support No | Opera Android Full support 46 | Safari iOS No support No | Samsung Internet Android Full support 8.0 | nodejs Full support 10.0.0 |
Legend
- Full support
- Full support
- No support
- No support