tournament.coffee

  $('.bracket').on('click', 'button.slot', () ->
    $.ajax(
      type: 'PUT'
      url: $('.update_path').text()
      data:
        position: $(this).data('position')
    )
  )

tournament_controller.rb

  def update
    tournament = Tournament.find(params[:id])
    if params[:position]
      tournament.advance(params[:position].map{|e| e.to_i })
    elsif params[:start]
      tournament.start
    end
    redirect_to request.referer
  end