Question

How can I freeze Javascript in firebug so that i can inspect the changes made by it in the html? If for example i have a jQuery rollover effect and i want to inspect the html code in that point in time.

I believe Dreamweaver CS4 has this feature titled freeze javascript and live code. Is there a free equivalent either in Firebug or another Firefox extension?

Answer 1

By “freeze” I assume you mean debugging, and yes, Firebug definitely has that.

First you have to go into the Script tab on Firebug. If Script is disabled on the site, enable it.

Now, go to the dropdown and select which JavaScript file you want to debug. This is typically either the page itself with inline JavaScript, or a linked page. Find the line of code you want to freeze on, and click to the left of the line numbers. You’ll see a red dot appear – this dot denotes that the code will freeze there during execution. Once the code is there, you can access the current HTML by going to the “HTML” tab. You’ll also see the icons in the top-right corner of Firebug’s Script pane light up, allowing you to either continue execution, step over, step into, or step out of each line of code, observing HTML changes for each line executed.

Note that Firebug lets you step through code line-by-line, which means that minimized JavaScript files (wherein all the code is compacted onto one line) are absolutely awful for debugging, because you can’t tell where Firebug is. So for debugging purposes, I highly recommend getting the non-minimized versions of files.

If you need more help, I suggest checking out the Firebug documentation, which has some good guides.