Best way to make an auto updater for node webkit games?

I don't know where to begin with this one. I want to have the game check if files stored online are the same as ones in the user's folder and to replace the out of date ones respectively with the online versions.

Can you be more precise ?

I just want to make an auto updater for my game in C2 if it can be done.

Edit: It needs to be a system that works in Node-Webkit because that's primarily what we're going to release our game on.

You should look at Ajax calls :

You upload a text file on your server, got it with Ajax and compare software version with Txt file version, then if you find new version, you download all the stuff.

Another solution is, if you have programming skills, you can do an external updater. I will do more researches later.

It is possible to update just some files with an update ?

because node webkit export pack the game files in one big file no?

Puchisoft Dispatcher is a pretty good updater maker which I use currently but it doesn't work with Linux or iOS. I guess until I find an alternate solution I'll make it run if the person is using Windows or send them to a download page if they're using Linux or iOS.

Which begs the question, how do I check which OS the person is running?