typescript - 什么 AsyncGenerator TypeScript 类型会产生 Promise？

Question

我正在尝试为下面的函数分配一个返回类型:

async function *sleepyNumbers() {  // what TypeScript type is this?
  let n = 0;
  while (true) {
    yield new Promise(resolve => resolve(n++));
    await new Promise(resolve => setTimeout(resolve, 500));
  }
}

(async () => {
  for await (const i of sleepyNumbers())
    console.log(i);
})();

生成器正在生成一个解析为 number 的 Promise。将类型设置为 Promise<number> 失败并显示以下错误消息:

TS2739: Type 'AsyncGenerator' is missing the following properties from type 'Promise': then, catch, [Symbol.toStringTag], finally

Iterable 导致了类似的错误。

我可以将类型设置为 AsyncGenerator 但这还不够具体。此函数的返回类型的正确 TypeScript 语法是什么？

Answer 1

它将是 AsyncGenerator<number, never, void> :
number - next 结果never 返回void - next 没有任何参数

您还需要明确键入一个 promise 解析:
yield new Promise<number>(resolve => resolve(n++));
全部一起:

async function *sleepyNumbers(): AsyncGenerator<number, never, void> {
    let n = 0;
    while (true) {
        yield new Promise<number>(resolve => resolve(n++));
        await new Promise(resolve => setTimeout(resolve, 500));
    }
}

(async () => {
    for await (const i of sleepyNumbers())
        console.log(i);
})();