If you have a function foo() that takes a callback as an argument i.e. something like:

  foo(..., function (n) {
     // closure over q, r, s
  });

Then what you can do is create a separate function, bar() that takes q, r, s as an argument, and returns a function:

  function bar(q, r, s) {
    return function(n) {
      // still has dependency on q, r, s
    }
  }

Once you have bar(), the foo() call above can be written as:

  foo(..., bar(q, r, s));

and you save one level of nesting. (This also makes the dependencies explicit, which is helpful.)

The main loop of

https://github.com/ithinkihaveacat/node-fishback/blob/ce5f9c...

does quite a lot of this, if you want a real example.