Can you run a test with the code in the article? I even said: "And that's still not ideal. We should be able to do: [code]".

I don't ever advise using map, but you can't setup your own for loop in coffeescript. Actually, in the code shown, map isn't used at all. Just .filter and .forEach.

Here is my version: http://jsperf.com/no-coffeescript-orig

The 'manual' is what I would write myself.