Setting a Conditional Breakpoint in Firefox with Firebug

Every once in a while I click randomly on something and realize that I’ve been an idiot. OK, sometimes it doesn’t require clicking on anything.

First off, if you’re working on client side code and you aren’t using Firefox with the Firebug add on, you should be. It gives you all the debugging capability that you need to win. (Some others swear by Chrome, but I’ve been developing with Firefox for a long time.)

Everyone else has probably known this for millennia, but I just figured out today that I can set a conditional breakpoint in Firebug. If you right click on a line where you’ve set a breakpoint (this was my random click), you get a syntax menu that looks something like this:

By selecting Edit Breakpoint Condition… you can add any valid JavaScript condition. Here’s one I used to break when I was processing row 55 in a loop:

Setting a condition like this is really useful, especially when you know that item 55 out of 4645 is causing an error and you just want to step through your script for that item.

There’s more to conditional breakpoints in Firebug [I know now], as you can read in the Firebug Tip: Conditional Breakpoints post on the Firebug blog.

Perhaps because I’m old school, while I’ve truly wanted to be able to set conditional breakpoints like this I’ve simply changed my indices or put in conditional debugging statements. I’ve gotten by just fine, but I’m going to be a lot more efficient now. If you didn’t know about this little trick, then hopefully you’ll be more efficient now, too.

Or maybe I’m just an idiot.