scroll messages to bottom + submit by key

chat-utils.js.coffee

$ ->
  submitByKey('.j-submit-by-key')

$ ->
  messagesEl = $('.j-messages-list')
  scrollToBottom messagesEl
  
  $('#new_message_form')
    .on 'ajax:success', (evt, data, status, xhr) ->
      messagesEl.append xhr.responseText
      scrollToBottom messagesEl
    .on 'ajax:error', (evt, data, status, xhr) ->
      console.log('scrollToBottom AJAX Error')

@scrollToBottom = (el) ->
  return if !el || el.length <= 0
  lastEl = $(el).children().last()
  firstEl = $(el).children().last()
  if !lastEl || !firstEl || lastEl.length <= 0
    return
  else
    scrollVal = $(el).children().last().position().top - $(el).children().first().position().top
    $(el).scrollTop(scrollVal)

@submitByKey = (inputSelector) ->
  allowSend = true
  $(inputSelector).focus ->
    $(inputSelector).removeClass('j-submit-by-key-active')
    $(this).addClass('j-submit-by-key-active')
    $(this).on 'keydown', (event) ->
      if event.which == 13 && !event.shiftKey && !event.ctrlKey && $(this).val().replace(/^\s+|\s+$/g, "").length > 0 && allowSend
        $(this).closest("form").addClass('j-form-active').submit()
        $(@).attr("disabled","disabled")
        allowSend = false
      else
        event.preventDefault
  $(document).on 'ajax:success', '.j-form-active', (evt, data, status, xhr) ->
    $('.j-form-active textarea').removeAttr('disabled').val('')
    $('.j-form-active').removeClass('.j-form-active')
    allowSend = true
  $(inputSelector+'[autofocus="autofocus"]').blur().focus()

form.html.haml

= f.input :body, :as => :text, :autofocus => true, :input_html => { :class => 'j-submit-by-key' }