Can we create socket instance by using socket = new io.Socket

[buzzshiva]

Can you let me know why the below case 1: doesn't work;
case 1:
var socket = new io.Socket('localhost', {port: 4000});
socket.connect();

but the case 2, works fine.
Case 2:
var socket = io.connect("http://localhost:4000/");

[rauchg]

var socket = new io.Socket('localhost', {port: 4000}).of('')

should work.