Symbol.asyncIterator

¥Value

众所周知的符号 @@asyncIterator。

¥The well-known symbol @@asyncIterator.

¥Examples

¥User-defined async iterables

你可以通过在对象上设置 [Symbol.asyncIterator] 属性来定义自己的异步迭代。

¥You can define your own async iterable by setting the [Symbol.asyncIterator] property on an object.

const myAsyncIterable = {
  async *[Symbol.asyncIterator]() {
    yield "hello";
    yield "async";
    yield "iteration!";
  },
};

(async () => {
  for await (const x of myAsyncIterable) {
    console.log(x);
  }
})();
// Logs:
// "hello"
// "async"
// "iteration!"

创建 API 时，请记住，异步迭代旨在表示可迭代的事物（例如数据流或列表），而不是在大多数情况下完全取代回调和事件。

¥When creating an API, remember that async iterables are designed to represent something iterable — like a stream of data or a list —, not to completely replace callbacks and events in most situations.

¥Built-in async iterables

核心 JavaScript 语言中没有异步可迭代的对象。某些 Web API（例如 ReadableStream）默认设置了 Symbol.asyncIterator 方法。

¥There is no object in the core JavaScript language that is async iterable. Some web APIs, such as ReadableStream, have the Symbol.asyncIterator method set by default.

¥See also

• 迭代协议
• for await...of