when-all-settled

Tiny javascript module that functions like javascript's Promise.all, but it does not mind if any of the promises reject.

Creates a Promise that resolves when all promises passed to it have settled (= either resolved or rejected). This is almost the same as Promise.all, except it does not reject if some of the given promises reject. Rejected promises simply result in a value undefined in the array of results.

DEPRECATED: Nearly the same function has been standardised in ES2020 as Promise.allSettled(…) Best to use that instead, if needed through e.g. Babel or adding a shim.

Install

npm install when-all-settled

…or equivalent.

Use

Example case, fetching some resources:

import whenAllSettled from 'when-all-settled'

const promises = [
  fetchSomething(),
  fetchSomethingThatWillFail(),
  fetchSomethingElse(),
]

whenAllSettled(promises).then(results => {
  // results contains [<Response>, undefined, <Response>]
})

API

whenAllSettled(promises, options)

Arguments:

• promises: an array of Promises to wait for.
• options (optional):

  • options.onRejection (optional): A rejection handler attached to each of the promises. The default logs the error to the console, unless process.env.NODE_ENV==='production'.

    Note: if this function throws an error, the returned promise rejects, and if it returns a value, that value will end up in the array of results.

Implementation

It's really just giving a more meaningful name to this one line of code:

promises.map(p => Promise.resolve(p).catch(onRejection))