Help! BC-Muse : Custom Code before closing Body tag

Question

I have a  project that is ongoing am constantly updating and publishing from Muse. I also have a custom code that is inserted before the closing body tag that I can't place in Muse (Because the feature is not supported). Every time I publish in Muse I lose this code because Muse will override the page always. So I have to go the code section in BC for the page and reinsert the code. This is giving me headache and stress on my back and sight.
How can I permanently place  this code before the closing body tag once without the stress mentioned earlier and without Muse re-writing the code for that specific page (I used to think Muse publish edited pages and not the entire site, even when the option to publish 'only modified pages is selected'). Please HELP!

Answer 1

Thanks Zak, this is the code:
  <script>
$('#pdropdown').change( function() {
$('#pdetails>*:not(.hide)').toggleClass('hide');
var optionVal = $(this).val();
$('#'+optionVal+'.hide').toggleClass('hide');
</script>
I have a web app that loads product list into a dropdown list. (How I wish we had a dropdown list form in Muse that can work with BC web app or a drop down list that can be use to target a specific  widget ID.) Maybe its time Muse widgets have ID so we can target them to appear by fading in, sliding in, etc.)