promise-results

Promise all results of a collection of promises whether they are resolved OR rejected.

Often we want to accomplish several asyncrounous tasks at once. Usually, Promise.all does what we want, but it has a couple limitations:

1. Rejections only provide rejection reason. Sometimes you want the data from Promises that did resolve, or you want to know specifically which items failed and which succeeded.
2. Requires a numerically indexed array. It's often more conveniant to label our parralel jobs with object keys than a flat index. promise-results will handle keyed objects or arrays.

Example

var resultsOf = require('promise-results');
var pack = {};
pack.a = Promise.resolve(2);
pack.b = a.then(function (r) {
  return new Promise(funciton (resolve, reject) {
    setTimeout(function() {
      resolve(r + 1);
    }, 10);
  })
});
pack.c = 42
pack.d = new Promise(function (resolve, reject) {
    setTimeout(function() {
      reject(new Error('Some random failure'));
    }, 10);
});
 
resultsOf(pack).then(function (results) {
  assert(results.a === 2);
  assert(results.b === 3);
  assert(results.c === 42);
  assert(results.d instanceof Error);
});

allKeys

If you just want to use objects, but want to keep Promise.all single rejection pattern, you can use the allKeys function instead.

Example

var allKeys = require('promise-results/allKeys');
var pack = {};
pack.a = Promise.resolve(2);
pack.b = a.then(function (r) {
  return new Promise(funciton (resolve, reject) {
    setTimeout(function() {
      resolve(r + 1);
    }, 10);
  })
});
pack.c = 42
pack.d = new Promise(function (resolve, reject) {
    setTimeout(function() {
      reject(new Error('Some random failure'));
    }, 10);
});
 
allKeys(pack).catch(function (err) {
  assert(err instanceof Error);
});

resultSet

If you like having a defined reject route, but still want access to your partial results and rejections. You can use resultSet.

Example

var results = require('promise-results/resultSet');
var pack = {};
pack.a = Promise.resolve(2);
pack.b = a.then(function (r) {
  return new Promise(funciton (resolve, reject) {
    setTimeout(function() {
      resolve(r + 1);
    }, 10);
  })
});
pack.c = 42
pack.d = new Promise(function (resolve, reject) {
  setTimeout(function() {
    reject(new Error('Some random failure'));
  }, 10);
});
 
results(pack).catch(function (result) {
  assert(result.d instanceof Error);
});