Modern best practice is to put the scripts a page uses at the bottom of the document, as long as they do not use APIs like document.write()
Doing so requires that the look-ahead parser scan through an entire document before finding them. As an experiment, my web app now emits this:
HTTP/1.1 200 OK
Link:</style/common.min.css>;rel=stylesheet prefetch, </scripts/common.min.js>;rel=script prefetch
however no difference above the statistical variance was noticed in the timing of speculative resource requests.
See http://stackoverflow.com/questions/3641581/link-rel-script-usage for comments about rel=script