app/assets/javascripts/registration_form.js.coffee
App.RegistrationForm =
initialize: ->
registrationForm = $("form#new_user[action=\"/users\"]")
usernameInput = $("input#user_username")
clearUsernameMessage = ->
$("small").remove()
showUsernameMessage = (response) ->
klass = if response.available then "no-error" else "error"
usernameInput.after $("<small class=\"#{klass}\" style=\"margin-top: -16px;\">#{response.message}</small>")
validateUsername = (username) ->
request = $.get "/user/registrations/check_username?username=#{username}"
request.done (response) ->
showUsernameMessage(response)
if registrationForm.length > 0
usernameInput.on "focusout", ->
clearUsernameMessage()
username = usernameInput.val()
validateUsername(username) if username != ""