I didn't know about the 3rd argument, thanks for this lesson.

PHP allows naive solutions to pass, other languages require a more optimized solution.

timed out ofc...

This certainly did not feel like a 7 kyu, especially with the optimization required for Javascript. I learned alot though, thank-you to the author.

In Javascript, the original number outside the function remains unchanged. This is because numbers are passed by value.

So good haha!

strings are immutable

Funny you say this now, yesterday I learned what XOR even was and that JS had an operator for it.

Draw a grid on a piece of paper and place a starting point on it, there you can experiment and test whether your logic is correct as well as find the solution.