"As it turned out, this seemed to be faster than the other two methods."

And yea, what you discovered is actually what I expected.

The compare halves only has to go through half of the string while the traversal from both ends has to create an array, reverse it, change it back to a string and then compare the original string with the current string…

That's one of the things I find most interesting about Javascript. Every time I think I know what is going to be fastest, I turn out to be wrong.

I've found that unless you really know the internal working of the Javascript implementation in your particular browser (and I'm sure there are some people that do, but I am not one of them), then there simply is no substitute for trying out your algorithm to see if it performs as you expected.

To be clear though, the splitting, joining and reversing wasn't faster in Javascript (did I somehow imply it was and not realize it?). The compare halves version was fastest in Javascript.

Personally, I would have expected the traversal from both ends to have been fastest.

Probably because implementation of those is in C and we are going through the array in JavaScript?

Compare halves should be significantly faster in other languages.

But so far as I can tell, your solution is conceptually the same as the second solution I outlined, albeit you did it with a bit less code, but it does not turn out to be faster than the "compare halves" version (at least, not in Javascript/Firefox).

This is the fastest method:

function pal(s)
{
var i, j,
len = s.length,

for (i = 0, j = len – 1; i < j; i++, j–)
{
if (s.charAt(i) !== s.charAt(j)) return false;
}
return true;
}