如何捕获异步函数引发的错误？

Question

try {
  const promise = new Promise(async (resolve, reject) => {
    reject('oe')
  })
  .catch(async (err) => {
    console.log('bbbbb', err)
    throw err
  })
} catch (err) {
  console.log('aaaaa', err)
}

Is is possible to make aaaaa loggable

Answer 1

In general, it doesn't make sense to pass an async function into a promise's then or catch function. And it never makes sense to pass one into the promise constructor. If you're going to go async , do it earlier. Also, when you want a rejected promise for testing, etc., just use Promise.reject('oe') .

In order to catch an error from an async function with a try / catch , you must be in an async function. In that case, the minimal change to your example would be to await the result of the call to catch :

// Assuming this is in an `async` function, making only minimal changes
try {
  const promise = new Promise(async (resolve, reject) => {
    reject('oe')
  })
  .catch(async (err) => {
    console.log('bbbbb', err)
    throw err
  })
  await promise;  // ***
} catch (err) {
  console.log('aaaaa', err)
}

If you aren't in an async function, you can't use try / catch to catch errors from promises (which includes from an async function call, since they return promises). Instead, you have to use the promise returned by catch :

// Assuming this is NOT in an `async` function, making only minimal changes
const promise = new Promise(async (resolve, reject) => {
  reject('oe')
})
.catch(async (err) => {
  console.log('bbbbb', err)
  throw err
})
.catch(err => {
  console.log('aaaaa', err)
})

---

Making larger changes, if you're already in an async function, get rid of the then and catch calls:

// Assuming this is in an `async` function
try {
  try {
    await Promise.reject('oe');
  } catch (innerError) {
    console.log('bbbbb', innerError);
    throw innerError;
  }
} catch (outerError) {
  console.log('aaaaa', outerError);
}

Answer 2

You can use async/await :

 async function test() { try { const promise = await new Promise(async (resolve, reject) => { reject('oe') }).catch(async err => { console.log('bbbbb', err) throw err }) } catch (err) { console.log('aaaaa', err) } } test()