Resolve a promise once all internal concurrent promises have resolved or rejected

Question

I am looking for something similar to Promise.all that will continue to resolve promises concurrently even in the event that one or more of the promises reject

Answer 1

You are essentially asking for a way to swallow any errors. As such, a function like this will be your best bet:

function swallow(p) {
  // transforms rejected promises into promises fulfilled with undefined
  return p.catch(function () { });
}

You would use it as follows:

Promise.all([swallow(fetch('url1.com')), swallow(fetch('url2.com'))]).then(function (data) {
  console.log('All requests finished', data); //data could be ['resultXML', undefined]
});

or even

 const promises = ['url1.com', 'url2.com'].map(fetch).map(swallow);
 Promise.all(promises).then(function (data) {
   // ...
 });