Discussion on: The dangers of async/await

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Replies for: Absolutely, thanks for catching my mistake. Must have made it while pasting my notes !

Absolutely! But there is a problem. If one of those will fail it will break all promise.all() iteration and you will be thrown into the catch. So I if you need/want to run fully async and parallel and get all results (errors and values) regardless of the failures you should use this:

 const promiseAllWithAllErrors = function(mapAsync) {
  return Promise.all(
    mapAsync.map(f =>
      f.then(r => Promise.resolve(r)).catch(e => Promise.resolve(new Error(e)))
    )
  )
}


promiseAllWithAllErrors([
   this.getConfig(),
    this.getUser(),
    this.checkRussianContext(query)
])

let's test it with some timeout function

const fun = function(txt) {
  return new Promise((yes, no) => {
    setTimeout(function() {
      if (txt === '2' || txt === '3') {
        no(txt + ' error')
      } else {
        yes(txt)
      }
    }, 5000)
  })
}

 promiseAllWithAllErrors([
  fun('1'),
  fun('2'),
  fun('3'),
  fun('4')
]).then(console.log)

output:

time node /tmp/t.js 
[ '1', Error: 2 error, Error: 3 error, '4' ]

real    0m5.205s.    ==> only 5 sec , instead of 5*4 and all answers in one array without interuptions  
user    0m0.071s
sys     0m0.044s