I'm not saying that my code is the most efficient, but I will say that I'm making a single pass through the array in javascript and timing out. I'd understand it if I were doing multiple passes but I don't understand why a single pass should ever make it time out.

On the Wiki page ( linked from the left menu ) there is a link "Creating your first kata" on the very first page. Read that in full, and look at the tests of kata you've solved - most any of them should have random tests.

Please note that "This is not new" is something that's hard to solve without real changes to your kata - you'll need to make your kata unique, because you can't very well unpublish other people's kata ..

NOTE: There will also be lists tested of lengths upwards of 10,000,000 elements. Be sure your code doesn't time out.

That's the reason, not unknown.