An Introduction to the Firefox 4 Web Console

One of the features that debuted in Firefox 4 is the Web Console. It allows users to peek behind the browser’s curtain to see what’s going on behind it.

Firefox 4 Web Console

Having some trouble with a Web site, just pop open the Web Console and see all kinds of information. You’ll see network traffic, HTML and CSS and JavaScript errors. A complex page like Walyou does generate a lot of information, including a lot of errors, even though it loads successfully. All this information is conveniently color-coded, as the screen shot shows. (Note that a lot of pages are written in ways that are outside of the platonic ideal of the Web standards in order to work properly on real Web browsers. Or old versions of Internet Explorer, to be exact.)

But the real prixe is the JavaScript REPL (Read-Eval-Print-Loop). Some of your might remember interacting what that old computer that used BASIC that they got you instead of that NES that was going to rot your brain. These computers usually ran a BASIC interpreter as the operating system. You could type in some code and have the computer do something interesting. Or more likely return an error, which you could learn from and retype it.

Mozilla has applied this concept to JavaScript. You can enter some JavaScript code and then have it run right in your browser. It’s a good way to try out ideas quickly to see what will happen. It’s also great if you’re learning Web development to get the hands on training you need to really learn the language.  In the book “The C Programming Language,” Brian Kernighan and Dennis Ritchie famously said the best way to learn a programming language is to actually write programs in it.

We’ve also covered Firefox with articles on the Tor browser,  a customized version that lets you browse anonymously, The Top 25 Firefox Extensions for Web developers, and the 11 Best Firefox Extensions for Facebook and Twitter.