What does this line of code reference: "var io = require('../..')(server);"? - sockets

Question

I followed this tutorial to create a chatroom using socket.io: https://github.com/socketio/socket.io.
I then created a page incorporating the chatroom (within the tutorial file structure) and now I am trying to export this into a different project...
I can't seem to do this without incorporating ALL the files from this tutorial.
I think I have narrowed down the issue to be this one line of code within the chat index.js page:
var io = require('../..')(server);
What does the above line reference to within the tutorial?
The error I get in my new project structure is this:
module.js:339
throw err;
^
Error: Cannot find module '../..'
Here is a link to the index.js file that has that line of code:
https://github.com/socketio/socket.io/blob/master/examples/chat/index.js

Answer 1

require() accepts a module name or a path to a module.
Per the node.js docs for require(), one of the argument options leads to this:
LOAD_AS_DIRECTORY(X)
1. If X/package.json is a file,
a. Parse X/package.json, and look for "main" field.
b. let M = X + (json main field)
c. LOAD_AS_FILE(M)
2. If X/index.js is a file, load X/index.js as JavaScript text. STOP
3. If X/index.json is a file, parse X/index.json to a JavaScript object. STOP
4. If X/index.node is a file, load X/index.node as binary addon. STOP
This would mean that ../.. is trying to go up the directory tree and load package.json, index.js, index.json or index.node from that directory.
You can read about the allowed syntax for require() here in the node.js docs.
FYI, there's a chat room demo on the socket.io site here.