Question

this is a classic question but can’t find the best approach. I have a dropdown with id project_billing_code_id and 3 values (1, 2, 3).

If value selected = 1 then show div with id one and only this one. div two and three must be hidden.
I also want to make this happen when view is loaded so not only on change.

$(document).ready(function() {
  $("#hourly").hide();
  $("#per_diem").hide();
  $("#fixed").hide();
$("#project_billing_code_id").change(function() {
  if ($("#project_billing_code_id").val() == '1') {
   $("#hourly").show();
   }
  else if ($("#project_billing_code_id").val() == '2') {
   $("#per_diem").show();
   } 
  else if ($("#project_billing_code_id").val() == '3') {
   $("#fixed").show();
   }
  else { 
       $("#hourly").hide();
       $("#per_diem").hide();
       $("#fixed").hide();
       }
  });
});

Answer 1

You were close. You probably want a few small tweaks to the behaviours to make sure all the divs hide and that correct div is showing on page load.

Have a play with the code here: http://jsfiddle.net/irama/ZFzrA/2/

Or grab the updated JS code here:

hideAllDivs = function () {
    $("#hourly, #per_diem, #fixed").hide();
};

handleNewSelection = function () {

    hideAllDivs();

    switch ($(this).val()) {
        case '1':
            $("#hourly").show();
        break;
        case '2':
            $("#per_diem").show();
        break;
        case '3':
            $("#fixed").show();
        break;
    }
};

$(document).ready(function() {

    $("#project_billing_code_id").change(handleNewSelection);

    // Run the event handler once now to ensure everything is as it should be
    handleNewSelection.apply($("#project_billing_code_id"));

});

Let us know how you go!