var a = 'nepal';
reverse this word without using any built-in function.
More on -
http://www.gufgaaf.com/Page/DisplayThread?threadId=15

var a = 'nepal';
var b = ';
for (var i = a.length - 1; i >= 0; i--) {
b = b+a[i];
}
//alert(b); will print lapen.

If you really want to test a developer on logic skills, use puzzles like this:
https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life (Just a sample.. there are plenty others like this)

May A_Guy is trying finish his/her assignments pretty quick.

Awesome @hamrochautari

These are interview question for full time jobs. You wont be asked language specific questions in full time job interview.
Better to share and practice...

Not sure where and what sort of companies ask you ONLY 'non-language specific' questions. And if you think the link I posted above is language specific, then you need to learn a lot.

BTW that was assignment I had to do on my recent interview within an hour. I dare you do that without any online lookup. Rules are pretty clear if you read.

@KaliKoPoi
Dude, we are not competing. We are learning and sharing. Whats your problem?

These type of questions are perfect candidate for any developer interview. I would say, this particular question is in easier side of the interview, probably for Entry level or Junior level position but definitely helpful to practice such questions.
As far as Kalikopoi's question, its a good problem to think about and try to solve at home but rarely any interviewer will ask in real interview. Most interviewer will have 1 hour or less time to test the candidate and in that time we have to test many aspect of candidate including logic problems. Problems that takes very long time are usually skipped.