Convention to where to declare module.exports on Javascript files

Question

Is there any convention to where we should declare the module.exports no Javascript/Node.js module files?

Should it be in the beginning of the file like:

module.exports = Foo;

function Foo() {
    this.bar = 'bar';
}

Foo.prototype.getBar = function() {
    return this.bar;
}

Or should it be in the end of the file:

function Foo() {
    this.bar = 'bar';
}

Foo.prototype.getBar = function() {
    return this.bar;
}

module.exports = Foo;

I know that there is no technical difference. The first example is perfectly valid because of declaration hoisting.

So I was wondering if there are some kind of best practices.

One advantage of leaving it on the end is that you can use function objects (`var Foo = function()...`), and yet another way of declaring it is directly (`module.exports.Foo = function()...`). — Marcelo, Jan 12 '16 at 15:47
I could just `var Foo = function Foo()...` and it would work as well. — Henrique Barcelos, Jan 12 '16 at 16:30
Advantage of putting it at the top: you can see the API of your module at a glance (without having to scroll down). — Adam Zerner, Dec 24 '16 at 18:45

Bruno Schäpper · Accepted Answer · 2018-07-06T12:48:56.940

There are certainly lots and lots of options, which are all commonly used. But that's terribly annoying. I like to put it at the end, because that works under all circumstances. Whenever I find myself doing something fancy with module.exports, there is probably a better way to do it.

Most importantly, as always, be consistent. And be consistent in your team.

EDIT: On the same notion, I like to have all require statements at the beginning. My Node.js files always look like this:

"use strict";

const fs = require("fs");
const MyClass = require("./MyClass");


class MyOtherClass extends MyClass {}

module.exports = MyOtherClass;

Nothing fancy, just the way you would expect it. One class per file, one file per class. Files named after the class they contain, with consisten upper/lowercasing. Have a look at this node module, for some examples: yaioc (disclaimer: I'm the author, and this is shameless advertising)

Convention to where to declare module.exports on Javascript files

1 Answers1