caching - at which extensions caches the browser a page -

we have web application.
until had no real cache handling strategy.
when had new version of javascript files, instructed our users clear browser cache.
want change this.
date our starting page "start_app.html".
in our effort implement our cache busting strategy want ensure browser not cache our starting page.
change extension ".html" ".php".
seems browser has array of extensions, when fetches fresh copy web server, "php", "asp", , on.
true , extensions these?
alot in advance

please don't rely on incorrect browser behavior not cache page. instead, use header:

cache-control: no-cache, no-store 

this page has details why header want.