express.js forms, new classes

I want to do something like this in express. I am using express-coffee https://github.com/twilson63/express-coffee

require "../forms/register"
exports.index = (req, res) ->
    rf = new registerForm
    rf.setField("username", "letters")
    res.render 'index'

I wrote in forms/register

class registerForm
  setField: (var1, var2) ->
    return "test"

But it doesn't work

How to write classes, import, extends them and using ?

You should export your form class explicitly:

module.exports = class RegisterForm
  setField: (var1, var2) ->
    return "test"

and explicitly reference what you require:

RegisterForm = require "../forms/register"

BTW, TitleCase for classes is a CoffeeScript convention.