Node: requiring module inside function?

Question

I was browsing the source code for a command line utility in Node, and saw the following code.

function help() {
    var colors = require('colors');
    var package = require('../package');
    ....
    ....
}

I had not seen require being used inside a function in this way before. I always assumed it was best practice to include it at the top of the file. This is the entry file for this program, and this function is only called in a specific case--but those packages are used elsewhere in the program. When I asked the author of the code for his reasoning, he simply stated that he "didn't want to import all the libraries at once."

Is this good/bad practice? Are there significant implications to load-up time by not requiring these packages at the top of the module, and instead only when these functions are invoked?

Answer 1

UPDATE: I think a better answer is here: Lazy loading in node.js

MY INITIAL COMMENTS: Well it's a matter of practice, some guys like it at the top while some like lazy-loading. In my opinion both are good, and should be used as per need, so I think that author is right here, because loading a whole bunch libraries at the startup would overload the module with much of the stuff that is never used, and hence would increase the load-time. And although loading the libraries on demand is a synchronous operation, but if we look help method as an entity, then it would give an asynchronous module loading effect (see AMD, which is a popular pattern).

Lazy loading is also a good selection if you have to make a choice between which libraries to load in a particular case, like for example

var isOSX;
// some code here which finds if this is OSX
// then this
if (isOSX === true) {
  var platformHelper = require('supercoolosxhelper');
} else {
  var platformHelper = require('yetanothercoolhelper');
}

In short, you should anticipate in your code if the probability of using a method is high or even mid, then you should require at the top, otherwise if it's low then it would be nice if the module is required on need basis.