Firefox 24 supports some parts of HTML5. More recent versions (like 37) support more features. You shouldn't be using such an old version of Firefox. Please update ASAP

Thanks Tylor, for your quick response.

then where can i get information on level of suppport provided by firefox 24.2.0 for HTML5 ?

TIA.

Here is a list of HTML5 support for Firefox 21, which is close to what 22 supports.

http://html5test.com/compare/browser/firefox-21.html

22 is not secure or supported anymore so you shouldn't be running it.

Btw the last security update for the old Firefox 24.X.x ESR was 24.8.1esr and not 24.2.0esr

The ESR has been based on Firefox 31.0 for a while now as current security update is 31.6.0esr besides the current Release which is [www.mozilla.org/firefox/all 37.0.1]