A hack to see if I can make a faster forEach shim.
JavaScript
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LICENSE.md
README.md
fasterForEach.js
perf_test.html
test.html

README.md

fasterForEach

A hack to see if I can make a faster forEach shim for IE8.

About

This is a hack that adds support for Array#forEach to IE8 but in a different way than the ES5 shim.

This basically rewrites the item processor (callback you pass into forEach) into a regular for loop and executes that (as oposed to executing the callback on each iteration). The result is that instead of 1 + n function invocations that you get with native or shimed forEach you get only two function invocations.

I created two nearly identical versions, the only difference is how the rewriten code gets executed. One uses eval and the other uses new Function().

Testing shows that both versions are faster than the ES5 shim. However I only have access to a VM from modern.ie running on a Macbook Air. But please visit this jsPerf test page and give it a spin so I can collect more data.

Is it usable?

I haven't tested this in any real project, but in theory I don't see why it couldn't be used.

License

Licensed under MIT. See LICENSE.md file for details.