Tuesday, September 20, 2011

Nodejs: module.exports and exports

I have just had a rough time learning how to create my own module. The problem is that I can't move on just knowing How to get something to work, I need to know Why. It is some form of programmer paralysis; worse than writers block. I needed to know how/why exports worked in Nodejs modules.

Requiring modules is simple

var m = require('./my_module');
m.myFunc(foo, bar);
The file needs to be "./my_module.js", with the following exports line:
var myFunc = function () { ... };
module.exports.myFunc = myFunc;
The Why is the hard part. You can't do exports = {}, but you can do module.exports = {}. Turns out module is the "global" namespace in an require() file. exports is some sort of "alias" for module.exports (I haven't figured that out). What this means is that exports.myFunc = myFunc; is OK, but exports = {myFunc: myFunc} is NOT OK, BUT module.exports = {myFunc: myFunc} is OK. Basically, I've decided not to use this pseudo-whatchamacalit "alias" type thing exports. I'll just use module.exports. Additionally, it is probably best to use the form:
module.exports.myFunc = function () {
for all exported functions inside ./my_module.js

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