LINK / CITE ADD TO WORD LIST. adjective. The definition of precious is something of great value or that is greatly loved. 1  An example of precious is priceless jewelry.
However, we can always point to the latest version under a particular category. The Current supported official version, which is the generally distributed and widely available latest version of Firefox, is Firefox 38.0.5. This version had an official release on June 2nd, 2015.
This guide includes some JavaScript features which are only currently available in the latest versions of Firefox, so using the most recent version of Firefox is recommended. There are two tools built into Firefox that are useful for experimenting with JavaScript: the Web Console and Scratchpad.