NodeJS callback out of sync

Asked Oct 19 '15 at 15:29

Active Oct 19 '15 at 15:29

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I'm pretty new to NodeJS and I am trying to solve the following problem related to callback functions.

var lib = require('someLibrary');

function main() {
  for(var i = 0; i <10; i++) {
    var num = someArray[i];
    lib.validate(function(result) {
      if(result.value === num) {
         console.log('Found it');
      }
    }
  }
}
main();

Now here since validate() takes a callback, my num is always out of sync. Any ideas on how to solve this problem?

asked Oct 19 '15 at 15:29

Omkar Sambhus

`var num =` -> `let num =` – Kevin B Oct 19 '15 at 15:31
@JamesThorpe it's the same problem in the end, just with 1 added step. – Kevin B Oct 19 '15 at 15:32
@KevinB Yeah - but I feel there's probably a better target for it than that Q – James Thorpe Oct 19 '15 at 15:33
[This one perhaps](http://stackoverflow.com/questions/7053965/when-using-callbacks-inside-a-loop-in-javascript-is-there-any-way-to-save-a-var) as it deals with the local variable, though it itself has been closed as a dupe of my first choice... – James Thorpe Oct 19 '15 at 15:35
@KevinB That worked. Thanks. How was this solved for ECMAScript versions <6 ? – Omkar Sambhus Oct 19 '15 at 17:25
@OmkarSambhus self executing functions, or using a functional iteration method such as [].forEach. An example of the former can be found at the canonical post James linked. – Kevin B Oct 19 '15 at 17:31
@KevinB Found it. Thanks :) – Omkar Sambhus Oct 19 '15 at 17:36

NodeJS callback out of sync

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