I use Firebug to debug webpages. I’m sure a lot of people do.

I also, find myself using “alert(variable)” quite often when debugging some JS that is infurating me at the time.

If you combine JS and Firebug, you can use console.log(variable); to show the variable value in the Firebug console instead of alerting it on a page. This, as I have learnt, is a much better way to debug code on a live site.