what does var io = require('../..')(server) do?

Question

I've build the project https://github.com/Automattic/socket.io/tree/master/examples/chat locally and it is working great. However, it would be nice to understand a little more about how a socket application works.

In the main startup script one of the modules that is pulled in with require is

var io = require('../..')(server)

what does require('../..') do?

thanks!

Answer 1

When a path to a directory is given to require, it will implicitly look for an index.js in that directory.

In this case, it's the equivalent of

var socket = require("../../index.js");
var io     = socket(server);

In the example provided, they're just using some shorthand and throw away the intermediate value returned by the call to require.

Check out the module.require docs for more info.