And then you spend hours trying to figure out the problem to no avail, leaving you scratching that magnificent head of yours with luscious, flowing hair. You just can’t replicate the problem. But then, after hours and days of staring intently at the screen, you find it. It’s a rogue console.log call that you forgot to comment out. And then you spend the remainder of the week chastising yourself for being stupid.
It happens. (To be fair, it’s not your fault that your users don’t have Firebug or IE Developer Tools installed. Blame it on Mozilla/Microsoft.)