Opera browser now has its own alternative to Firefox' Firebug
Recently, Opera's developers have been touting it as the most compliant browser with Web standards. Now they're using that as leverage to help introduce Dragonfly, a tool they hope will promote Opera as a kind of standards watchdog.
Easily among the most useful and well thought-out extensions to Mozilla Firefox has been Firebug, an add-on by independent developer Joe Hewitt which instantly converts any active Web site into a fully-fledged JavaScript/XHTML/CSS/DOM diagnosis studio. You can see why an element is parsed and laid out the way it is by pointing at it, and letting Firebug take you to the code in question. Up until now, no tool with similar functionality and reliability has existed within the browser context; Microsoft's Web development tools are centered around Visual Studio and Expression.
Today, it's Opera which is changing that picture, with the introduction of its own live development environment add-on called Dragonfly, whose alpha version was released yesterday. It's produced by the Opera team itself, is recommended for recent builds of version 9.5, and is being billed not only as a Web development environment but also as a standards conformance tool.
With Opera reportedly scoring very high or perfect in recent Web Standards Project conformance tests, its creators may see Dragonfly as a way to build Opera into more than just a browser, but a development tool in itself.
According to a blog post from Opera developer relationship manager Chris Mills yesterday, Dragonfly makes use of monitoring tools that are now actually built into Opera itself, called Scope. Like Firebug, Dragonfly includes a JavaScript debugger and CSS and DOM inspectors in a separate Developer Tools window, which also includes a command line that lets you interact with a JavaScript parser in immediate mode.
The script window permits line-by-line execution stepping through individual instructions or between procedures, with variable breakpoints. Once execution of JavaScript has reached a breakpoint and pauses, the window can give you a full report of the state of the page's DOM and the contents of any active JavaScript variables.
Perhaps most importantly, Dragonfly is capable of providing a very detailed error and warning report within its Console tab.
The early reviews are mixed, with some impressed by how quickly Dragonfly responds, others depressed with how slowly it can load. The developer of the Python Web site framework Django, Simon Willson, expressed on his personal blog a viewpoint that's currently somewhere in-between: "Out in alpha and it shows (slow to load and the interactive console leaves a lot to be desired)," Willson wrote, "but still looks incredibly promising, especially the remote debugging tools for working with Opera on phones and games consoles."
Dragonfly's Web site is also promising that, in order to keep it adherent to the latest standards at all times, its final release versions will be self-updating, without user intervention. It will be distributed freely under the BSD license.