javascript - 等待异步函数

Question

有没有办法等待异步函数？像 yield* (带有星号)这样的东西将委托(delegate)给另一个生成器函数。

例如:

asyncFunction1 = async () => {
    await promise1;
    await promise2;
}

asyncFunction2 = async () => {
    await asyncFunction1(); // can we do that or it MUST be a promise?
}

Answer 1

标记函数async使其隐式返回一个promise:

When an async function is called, it returns a Promise. When the async function returns a value, the Promise will be resolved with the returned value. When the async function throws an exception or some value, the Promise will be rejected with the thrown value.

( source )

换句话说，您可以在异步函数上 await，即使该函数返回非 Promise 值(因为该值将自动用 Promise 包装):

async function test() {
  return 123;
}

void async function() {
  let value = await test();
  console.log('value', value);
}();