Style proposal: async/await vs .then()

I’ve seen there’s a mix in the code where sometimes async/await is used and sometimes somePromise.then().catch(). I’d like to propose to homogenize the code by using always async/await, and I offer myself to make the PR should the proposal be accepted.

Also, if it’s accepted, it should be added to the contribution guideline.

[fernandocanizo]

To @am2222

Why not to use then().catch()?

async/await allows for cleaner code style.

Also, sometimes you need to use a result from previous calls, and it’s cleaner to do:

// ...
try {
  const aResult = await calculateA();
  const bResult = await calculateB();
  const finalResult = await calculateFinal(aResult, bResult);
  return finalResult;
} catch (e) {
  console.error(e);
  // ...
}

Than:

// ...
return calculateA()
  .then(aResult => calculateB()
    .then(bResult => calculateFinal(aResult, bResult))
  .catch(e => console.error(e));

In addition, there’s a subtle thing to consider on the last snippet: if you were to use a block instead of an inline function on the anidated .then like:

  // ...
  .then(bResult => {
    // ... some other statements
    return calculateFinal(aResult, bResult);
  })
// ...

You need to ensure you’re returning the inner promise for the outer .catch() to catch possible errors from the inner promise. Or use a double .catch(). Thus, this style can induce you to make errors. For example if you were refactoring the one-liner into a block and forget to return the promise and put the inner .catch() you’ll end up with an unnoticed bug until you get an UnhandledPromiseRejectionWarning.

Consider I gave a very simple example with 2 calls. What would the code look if you need 5 or 10 different asynchronous calls under the same function?

Quoting Douglas Crockford from memory: “If one coding style can induce you to make errors and other not, then use the later”.

Aim to avoid the cognitive load always.

[hagopj13]

@fernandocanizo I have tried to (mostly) use async/await, except for a few exceptions, which I just counted as 4 occurances. These are mainly to avoid top-level-await and Promise.all. If you have any suggestions on how to change these as well, please go ahead and make a PR.