Try executing the following in JavaScript:

parseInt('01'); //equals 1

parseInt('02'); //equals 2

parseInt('03'); //equals 3

parseInt('04'); //equals 4

parseInt('05'); //equals 5

parseInt('06'); //equals 6

parseInt('07'); //equals 7

parseInt('08'); //equals 0 !!

parseInt('09'); //equals 0 !!

I just learned the hard way that JavaScript thinks the leading zero indicates an octal integer, and since there is no 8 or 9 in base-8, the function returns zero. Like it or not, this is by design.

What are the workarounds?

Note: For sake of completeness, I'm about to post a solution, but it's a solution that I hate, so please post other/better answers.

Update:

The 5th Edition of the JavaScript standard (ECMA-262) introduces a breaking change that eliminates this behavior. Mozilla has a good write-up.