<script type="text/javascript" src="somenamehere.js"></script>
</body></html>
but i can't find a write up quick enough to explains the whys.
make div #blah blue
and div #blah hasn't loaded yet, then the script will do nothing even once the div is loaded in memory.
<img class="slide" src="https://github.com/lantech19446/mypictures/blob/master/1024px-Reddit.svg.png?raw=true"
chrome://site-engagement/
is a very interesting page.