Recently, I’ve been spending a lot of time analyzing the speed of pure JavaScript engines, looking at how well they perform and what their particular strengths and weaknesses are. To start with, I analyzed the bleeding-edge code from:

Right now I’m only looking at pure, JavaScript-only, tests (no tests of DOM or other APIs) and am NOT looking at the speed of the browsers’ native JavaScript engine implementations. (So, even though you may see a speed for a particular engine, that does not directly correlate to the speed of the JavaScript running within the browser itself. There’s always a significant amount of overhead required to run JavaScript code seurely within a browser, thus the efficiency of that security layer will frequently become a deciding factor in the results.

The four engines that I picked all had complete JavaScript implementations and usable JavaScript shells (that way I could feed my tests in and have them cleanly run).

To browse the results I’ve pulled together a simple application that can be used to view a representation of the data from all the major JavaScript engines paired with the code from the tests which run them.

Right now the browser works fine in Firefox, is quirky in Opera and Safari, and explodes in IE (it requires canvas support). I’ll finesse it into shape when I have a little more time this week.

Note: This demo uses a bunch of functionality from the new jQuery UI library, including themes, tabs, accordion, and resizables.