Question

我正在尝试处理（节点：29804）UnhandledPromiseRejectionWarning：test1首先抛出 ，有人知道我该如何处理吗？在这种情况下，我对使用await不感兴趣。

const test0 = async () => {
  try {
    throw('test0 first throw');
  }
  catch(e) {
    console.log('test0 last catch');
    throw('test0 last throw');
  }
}

const test1 = async () => {
  try {
    test0()
    .catch(e => {
     console.log('test1 first catch');
     throw('test1 first throw'); // This throws unhandled exception
    })
//    return(0);
  }
  catch(e) {
    console.log('test1 last catch');
    throw('test1 last throw');
  }
}

const caller = async () => {
  try {
    let res = test1().
      catch(e => {
        console.log('PRE FINAL CATCH');
      })
    console.log(res);
  }
  catch(e) {
    console.log('FINAL CATCH');
//    console.log(e);
  }
}

caller();

Answer 1

看到try/catch和then()/catch()样式的混合处理承诺很少见。

您可以删除所有不必要的try / catches和return。不涉及await。如果其他函数中的某处发生错误，则会记录该错误并将其返回到caller：

const test0 = async () => {
  try {
    throw('test0 first throw');
  }
  catch(e) {
    console.log('test0 last catch');
    throw('test0 last throw');
  }
}

const test1 = async () => {
  return test0()
    .catch(e => {
     console.log('test1 first catch');
     throw('test1 first throw'); // This throws unhandled exception
    });
}

const caller = async () => {
  return test1().catch((e) => {
     console.log('PRE FINAL CATCH');
  });
}

caller();

如果还有其他要求，我很乐意修改此答案。

Answer 2

感谢您的回复，我最后在这里进一步了解了异步错误处理的工作原理：https://medium.com/javascript-in-plain-english/javascript-async-function-error-handling-is-not-what-you-think-dac10a98edb2

并最终使用此代码结构。这个想法对异步和等待的函数具有类似的函数结构和错误处理。在此示例中，我更喜欢try / catch块的原因是因为它将捕获该函数中可能存在的所有其他错误

//如果无法在调用者函数中使用await，请遵循结构A

/ *************开始结构A ************* /

const handlerFnA = async(fnParam) => { await fnParam(); }

const fnDispatcherA = async () => {
  try{
    await handlerFnA(innerAsyncFnA);
  }
  catch (e){
    console.log('error caught in fnDispatcher: ', e);
  }
}

const innerAsyncFnA = async () => {
  try {
    throw('I am an error from innerAsyncFn');
  }
  catch(e) {
    console.log('innerAsyncFn catch');
    throw(e);
  }
}

const callerA = async () => {
  try {
    fnDispatcherA();
  }
  catch(e) {
    console.log('caller catch');
  }
}

/ ***********结束结构A ************ /

//如果可以在调用方函数中使用await，请遵循结构B

/ *************开头结构B ************* /

const handlerFnB = async(fnParam) => { await fnParam(); }

const innerAsyncFnB = async () => {
  try {
    throw('I am an error from innerAsyncFn');
  }
  catch(e) {
    console.log('innerAsyncFn catch');
    throw(e);
  }
}

const callerB = async () => {
  try {
    await handlerFnB(innerAsyncFnB);
  }
  catch(e) {
    console.log('caller catch');
  }
}

/ ***********结束结构B ************ /

callerB();

未处理的拒绝

2 个答案: