How to make a function wait until a callback has been called using node.js

I have a simplified function that looks like this:

function(query) {
  myApi.exec('SomeCommand', function(response) {
    return response;
  });
}

Basically i want it to call myApi.exec, and return the response that is given in the callback lambda. However, the above code doesn’t work and simply returns immediately.

Just for a very hackish attempt, i tried the below which didn’t work, but at least you get the idea what i’m trying to achieve:

function(query) {
  var r;
  myApi.exec('SomeCommand', function(response) {
    r = response;
  });
  while (!r) {}
  return r;
}

Basically, what’s a good ‘node.js/event driven’ way of going about this? I want my function to wait until the callback gets called, then return the value that was passed to it.