amper-promise-utils

Ampersand's utility functions for using promises and async-await.

parallel()

Waits for all promises passed in to settle (unlike Promise.all, which will reject immediately upon first error).

parallelWithErrors()

Waits for all promises passed in to settle (unlike Promise.all, which will reject immediately upon first error). Returns errors instead of throwing them, so caller can cleanup anything that succeeded.

class ParallelQueue

Runs async jobs in parallel, with a maximum parallelization count. Requires jobs to be added by function name and parameters, so they can be started later.

const jobs = new ParallelQueue(10);
for (const userID of users) {
  jobs.collate(userID, fetchUserInfo, userID);
}
const userInfos = await jobs.run();
for (const userID in userInfos) {
  console.log(userInfos[userID]); // fetched user info
}

forever()

Returns a Promise that never resolves; used in cases where you want to enter an infinite event-handling loop.

sleep(ms: number)

A Promise-wrapped version of setTimeout.

class ActionTimeout

Runs an async function but early-out rejects if it takes longer than some timeout.

ignoreError()

Used to wrap a Promise with another Promise that will resolve instead of reject if the original Promise rejects with an error that matches any of the given error strings.

const val = await ignoreError(someAsyncFunc(arg0, arg1), 'not found', 'offline');

withError()

Used to wrap a Promise such that it returns any error instead of throwing it.

const { err, data } = await withError(someAsyncFunc(arg0, arg1));
if (err) { ... }