(JavaScript) Synchronizing forEach Loop with callbacks inside

Take a look at async.js, and especially its control flow statements, such as each whilst and until.

Using async.js you can get what you want to have.

In your actual situation what you want is the each function (which has formerly been known as forEach), respectively the eachSeries function which does not run the single iterations in parallel, but in serial (see the documentation for eachSeries for details).

To provide an example:

async.eachSeries([ 2, 3, 5, 7, 11 ], function (prime, callback) {
  console.log(prime);
  callback(); // Alternatively: callback(new Error());
}, function (err) {
  if (err) { throw err; }
  console.log('Well done :-)!');
});

This will iterate over the array of prime numbers and print them in the correct order, one after each other, and finally print out Well done :-)!.