Question

I’ve started to use Javascript a lot more, and as a result I am writing things complex enough that organization is becoming a concern. However, this question applies to any language that allows you to nest functions. Essentially, when should you use an anonymous function over a named global or inner function?

At first I thought it was the coolest feature ever, but I think I am going overboard. Here’s an example I wrote recently, ommiting all the variable delcarations and conditionals so that you can see the structure.

function printStream() {
  return fold(function (elem, acc) {
    ...
    var comments = (function () {
      return fold(function (comment, out) {
        ...
        return out + ...;
      }, '', elem.comments);
    return acc + ... + comments;
  }, '', data.stream);
}

I realized though (I think) there’s some kind of beauty in being so compact, it is probably isn’t a good idea to do this in the same way you wouldn’t want a ton of code in a double for loop.

Answer 1

Like any tool, it depends. You shouldn’t always use it nor should you never use it. You should use it where appropriate.

You should use them where it’s a simple 2 or 3-liner and there is no application for using it anywhere else.

You should use it in JavaScript where you gain a closure to isolate variables in the deal.

Above all, as long as another developer can look at the code and “get it”, it’s just fine. When I look at the code sample above, I do not “get it.”