Any Javascript optimization tests?

I watched Nicholas Zakas' story, Speed ​​Up Your Javascript , with some interest. I liked how he compared different performance improvements created by different optimization techniques, for example. reducing calls to deeply nested objects, changing loops to count down instead of up, etc.

I would like to run these tests myself to see exactly how our current browsers are performing. I think it wouldn't be too hard to prepare a few timed loops, but I would like to know if there are any existing implementations out there.