gistfile1.js

var doStuff = function(val, cb) {
  // Call the callback later!
  setTimeout(function() { cb(val); }, 1);
}

var total = 5;
for (var i = 0, c = 0; i < total; ++i) {
  doStuff(i, function(val) {
    console.log('Got a return value! ' + val);

    if (++c === total) {
      console.log('All 5 are done');
    }
  });
}

console.log('This debug statement will appear first! Weird, huh...');