Unbounce - Conditional form field (base)

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script>

<script>
  /*
Unbounce Community :: Tips & Scripts :: Conditional State/ Province Form Field Based on Dropdown 
TS:0002-04-060
***********************
Do not remove this section. It helps our team track useage of external workarounds.
*/ 
(function(){
  //ID of Submit Button
  var submitBtn = $("#lp-pom-box-28"); 
  
  //ID of dropdown field
  var field = $("#quel_campus_vous_intéresse_");
  
  // Number of fields to show/hide with dropdown
  var count = 10;
  
  // Adjust to fine tune placement of other form fields
  var space = 100;
  
  // Add the ID of the containing element (box) of your form if one exists
  // Leave as "" if there is no box containing the form.
  var box = "#lp-pom-box-28";
  
  
  // DO NOT EDIT CODE BELOW
  var conFields = field.parent().nextAll().slice(0, +count);
  var moreFields = field.parent().nextAll().slice(count);
  var topPos = conFields.first().position().top;
  
  // function to add the heights of all fields selected 
  $(conFields).each(function() {
    $(this).css({top: topPos}); 
    var height = $(this).outerHeight(true);
    space = space += height;
  });
  // hide fields
  conFields.css("display", "none");
  // position other form fields
  $(moreFields).each(function() {
    $(this).animate({top: "-=" + space},0);
  });
  
  // function to show/hide fields
  var z = true;
  var box = $(box);
  $(field).change(function() {
    
    // adjust position of fields
    var fieldAdjust = function(h, dir) {
      if (dir == "up") {
        $(moreFields).each(function() {
          $(this).animate({top: "+=" + (h+5)}, 600)
        });
        submitBtn.animate({top: "+=" + (h+5)}, 600);
        if (box != "") {
          box.animate({height: "+=" + (h+5)}, 600);
        }
      } else if (dir == "down") {
        $(moreFields).each(function() {
          $(this).animate({top: "-=" + (h+5)}, 600)
        });
        submitBtn.animate({top: "-=" + (h+5)}, 600);
        if (box != "") {
         box.animate({height: "-=" + (h+5)}, 600);
        }
      }
    }  
    var fieldGroup = range(0, count);
    if ((this.selectedIndex - 1)in fieldGroup) {
      var revealNum = this.selectedIndex-1;
    } else {
      var revealNum = -1;
    }
    var revealField = conFields.get(revealNum);
    var otherFields = conFields.not(revealField);
    var fieldHeight = $(revealField).outerHeight(true);
    if (revealNum in fieldGroup) { 
      $(revealField).fadeIn("slow");
      $(otherFields).fadeOut("slow");
      if (z) {
        fieldAdjust(fieldHeight,"up");
        z = false;
      }
    } else {
      $(revealField).fadeOut("slow");
      $(otherFields).fadeOut("slow");
      fieldAdjust(fieldHeight, "down");
      z = true;
    }
    
  });
  function range(start, end) {
    var array = new Array();
    for(var i = start; i < end; i++) {
        array.push(i);
    }
    return array;
  }
})();
</script>