异步迭代

【Async Iteration】

<ReadableStream> 对象支持使用 for await 语法的异步迭代器协议。

【The <ReadableStream> object supports the async iterator protocol using for await syntax.】

import { Buffer } from 'node:buffer';

const stream = new ReadableStream(getSomeSource());

for await (const chunk of stream)
  console.log(Buffer.from(chunk).toString()); 拷贝

异步迭代器将会消耗 <ReadableStream> 直到它终止。

【The async iterator will consume the <ReadableStream> until it terminates.】

默认情况下，如果异步迭代器提前退出（通过 break、return 或 throw），<ReadableStream> 将会被关闭。要防止 <ReadableStream> 自动关闭，可以使用 readableStream.values() 方法获取异步迭代器，并将 preventCancel 选项设置为 true。

【By default, if the async iterator exits early (via either a break, return, or a throw), the <ReadableStream> will be closed. To prevent automatic closing of the <ReadableStream>, use the readableStream.values() method to acquire the async iterator and set the preventCancel option to true.】

<ReadableStream> 不得被锁定（即不得已有活动读取器）。在异步迭代期间，<ReadableStream> 将被锁定。

【The <ReadableStream> must not be locked (that is, it must not have an existing active reader). During the async iteration, the <ReadableStream> will be locked.】