gistfile1.js

var async = require('async');

function some (items, iterator) {
  var ret = -1,
      v;
  
  for (var i in items) {
    v = iterator(items[i]);
    
    if (v) {
      ret = i;
      break;
    }
  }
  
  return ret;
}

async.parallel([
  function (done) {
    done(null, null);
  },
  function (done) {
    done(null, 'filePath');
  },
  function (done) {
    done(null, null);
  }
], function (err, results) {
  if (err) {
    throw err;
  }
  
  var idx = some(results, function (i) { return !!i; });
  // => 1
  
  if (idx === -1) {
    throw new Error("File not found");
  }
  
  console.log('Found file', results[idx]);
  // => 'filePath'
});

function find(collection, filter) {
    for (var i = 0; i < collection.length; i++) {
        if(filter(collection[i], i, collection) return i;
    }
    return -1;
}

Does the same thing in a less confusing way :P