重试失败的异步/承诺功能？

Question

我有这个异步块：

test().then(function(result){
    // Success: Do something.
    doSomething();
}).catch(function(error){
    // Error: Handle the error, retry!
    // How to re-run this whole block?
});

我可以跟踪的success和failed成果。但是，test().then().catch()如果我们失败了，是否可以重试整个链？并继续重试直到条件解决？

Answer 1

如果可以切换到async/await语法，则可以使用while循环：

let keepTrying;

do {
    try {
        await test();
        keepTrying = false;
    } catch {
        keepTrying = true;
    }
} while (keepTrying)

doSomething();

然后，您可以将重试逻辑抽象为自己的函数以供重用。

Answer 2

您可以将整个事情放入一个函数中，如果catch进入该块，该函数会递归地调用自身：

function tryTest() {
  return test().then(function(result) {
    // Success: Do something.
    doSomething();
  }).catch(function(error) {
    // error handling

    // make sure to return here,
    // so that the initial call of tryTest can know when the whole operation was successful
    return tryTest();
  });
}


tryTest()
  .then(() => {
    console.log('Finished successfully');
  });

如果您doSomething可以接受result参数，并且如果tryTest不接受任何参数，则可以将上面的内容简化为：

function tryTest() {
  return test()
    .then(doSomething)
    .catch(tryTest);
}


tryTest()
  .then(() => {
    console.log('Finished successfully');
  });