application.js

$(document).ready(function(){
  //$('form input[type="text"]:first').attr("tabindex", 1);
  var first_field = ($('form input[type="text"]:first').attr('name'));
  var form = ($('form:first').attr('id'));
  //alert (form + "- " + first_field);
  if (first_field == "task[due_date]") {
    $('form textarea:first').focus();
  }
  else
  {
    $('form input[type="text"]:first').focus();
  }
});