Much has been said about TraceMonkey and the JavaScript improvements that have been made in the browser. There are two basic ways to test this from an end-user's perspective:

• Performance measurement
• Hunting down crashes while exercising the JS engine.

Reliable performance measurement is really hard for someone to do by just eye-balling the computer. If you can see it working then it's too slow to ship :) However, hunting down crashes can be easy and fun. We need to think about big, complicated sites here with a lot of "stuff" going on. Those are the sites using lots of Javascript, I'll make some suggestions, but feel free to find your own too.

Testing Suggestions

• Play JavaScript Games! These games are all based in JavaScript and will probably use some unusual code patterns.
• Check out big sites like Google Mail, Yahoo Mail, Facebook, Myspace, ESPN. These sites have a substantial amount of JS going on. In general, the more AJAX-y a page is, the more javascript it is using.
• We've seen lots of interesting behaviors with Automotive sites, so go shopping for that dream car.
• Try out doing some online photo rendering, that will eat some JS!
• And finally, yes a bunch of JS animations. I wonder what would happen if you looped a bunch of these and ran them in fifty tabs simultaneously? And what if you did a crash + session retore in the middle of that? Find out!

Get creative and have fun.