Cross-platform, cross-browser Javascript performance profiling

In addition to my recent question on server-side profiling of a PHP a开发者_开发知识库pp, an app can have a ton of javascript, being all AJAXy in content.

This begs the question of cross-platform, cross-browser javascript profiling tools - do they exist, what ones do people use, and what benefits are there for each one?

Much appreciated.

http://testswarm.com/

you may do profiling in firebug, dont know about chrome's console though

Check out HTML 5 Boilerplate.

It includes a Javascript profiler that works for IE6/7 as well. Watch the video on further explanation on how to do this. There are lots of other neat stuff in there too related to latest web standards/practices.

If your code is abstracted well, using good cross-browser frameworks and libraries, and avoid using native JavaScript wherever possibile, you should not worry about having tools to help you test across all different browsers.