Opera Releases Firebug Alternative: Dragonfly

For web developers, and especially front-end coders, the Firefox extension Firebug by Facebook’s Joe Hewitt is a killer app and major time saver. It lets you deconstruct the webpage currently loaded into Firefox to get a better idea of how HTML, CSS, and JavaScript needs to be modified to work properly (and it can even make changes to CSS on the fly).

Opera has just released a competing set of developer tools called Dragonfly. They will be automatically included in Opera 9.5 beta 2 and newer versions of the browser, and you will be able to enable them by going to “Tools > Advanced > Developer Tools”.

The Norwegian software maker is highlighting several innovative features of Dragonfly that could give it a leg up on Firebug, all depending on how well they work.

Dragonfly will make it possible to debug webpages whether they’re on your desktop computer or any remote device, like a cellphone, that runs the Opera browser. This has the potential to make development for mobile devices much easier.

To JavaScript programmers’ delight, Dragonfly will also show the most up-to-date document object model (DOM) of a page, not just its initial construction. This means the effects of dynamic changes to a webpage, whether Ajax-driven or not, will now be much more transparent and traceable.

Dragonfly is also said to have a sophisticated JavaScript debugger that lets you diagnose errors on a line-by-line basis. JavaScript notoriously lacks any real debugging capabilities so this feature holds a lot of promise for developers tired of inserting alert functions throughout their code to see where it breaks.

A couple downsides: it will only be available for Opera, certainly not one of the most widespread browsers, and it won’t initially support in-browser edits to CSS styles. This latter shortcoming is a big one since CSS editing constitutes perhaps the most useful feature of Firebug.

Dragonfly will be released as open source under the BSD license. Microsoft announced at MIX that it has also worked on a set of developer tools for Internet Explorer 8, still in early beta.