How to make enter behave like tab in dynamic form

I found a solution that seems to work fine with Internet Explorer. The problem I needed to solve was to make the enter-key behave like the tab-key in a form. The problem was that since the form could look different depending on previous user input I was unable to know the tabindex of the next field for sure (the "steps" in the tabindex could be 1, 5 or 10 between form fields). Also I was unable to use the .element[] feature of the form to find the correct (next) field by just getting the next element in the array.
The forms[0] reference of course gets the first form in the document and is hardcoded in this code, you may choose to make a more clever function, I didn't bother...

I trigger this function on the "onKeyup()" event like this (placed in the <form> tag) onkeyup="tabIfEnter(event)".

Here is the Script code to make it work:
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function tabIfEnter(event)
{
if(event && event.which)
{
var e=window.event;
var charCode=e.which;
}
else
{
var e=window.event;
var charCode=e.keyCode;
}
if (charCode == 13)
{
var x = document.forms[0].length;
var nextElement = document.forms[0].elements[x-1]; //Gets the last element in the form
var currentTabIndex = window.event.srcElement.getAttribute('tabindex'); // Gets the tabindex of current field

//if current field is the last set focus on the first in the form
if (window.event.srcElement.name == nextElement.name)
{
document.forms[0].elements[0].focus();
return;
}

//find a field that has a tabindex higher than current field and lower than the last (or any found previously)
//by looping through entire form
for(elementnum = 0; elementnum < x; elementnum++)
{
if ((document.forms[0].elements[elementnum].getAttribute('tabindex') > currentTabIndex) &&
(document.forms[0].elements[elementnum].getAttribute('tabindex') < nextElement.getAttribute('tabindex')))
{
//replace with better match than the one we had
nextElement = document.forms[0].elements[elementnum];
}
}
nextElement.focus();
return;
}
else
{
window.event.srcElement.focus(); //set focus on current field
return;
}
}
[/color]
Hope it can save somebody else some time. I haven't tried the script on any other platforms than IE since it is only used in an intranet.

//Jonas