Grab it here: Inspector Milestone 0.5 Preview.

Other work that’s moving along nicely:

• Neil Deakin’s ongoing improvements to XUL Panels.
• David Dahl’s work on the Heads Up Display
  
• Firefox 4 Theme work is beginning to land

… Just to name a few.

We also picked up some help from some members of the Bespin team this week. We’re still figuring out what people are going to work on, but it looks like Julian Vierick is going to do some Inspector<->Console cross connection stuff with the DOM Panel. And maybe, just maybe, Joe Walker is going to help me make the Inspector look pretty. I am hopeful.

Give the preview a try and let me know what you think. Feel free to file bugs in Firefox::Devtools.

Update: After the rebasing, I’ve cloned another user repo for ongoing work. It’s too much of a pain to reintegrate patches from a point in time and merge everything together in a way that won’t mung up a future extraction. And cloning is cheap. If anyone has a good idea of how to “applepick” in hg, I’d love to hear it.

New repo is here: http://hg.mozilla.org/users/rcampbell_mozilla.com/mozilla-inspector-3

To be sure, there are some bugs left. Clicking the twisty images still doesn’t expand and collapse the trees – you need to click on the tag to do that. It’s still behaving funny with iframes. I still need to revise the styling for the tree panel and other panels to make it look like I want. I need to add some keyboard controls…

All of this will need bugs filed and patches written. If you’d like to help, please feel free to file bugs on the Firefox::Devtools component. Make sure to use Inspector in the subject or whiteboard so we can track it. We also have a #devtools IRC channel on irc.mozilla.org if you’d like to pop in and say hi.

Other bits I have left to do include verifying my existing test cases and writing a few new ones. There’s a lot of debugging code I need to strip out and lastly, I’ll need to rebase my patches against current mozilla-central and roll it all up into a nice tidy patch for my reviewer victim… I mean friend. Before that though, I hope to churn out some try builds tomorrow or Wednesday for people to play with.

If you want to check out the source and build your own, it’s living in http://hg.mozilla.org/users/rcampbell_mozilla.com/mozilla-inspector-2/. Careful, it’s fluxy!

Currently, we include View Source in Firefox 3.6. I’ve blogged about how important view source is and how awesome it is that we have it, but inspection is a different kind of activity. Whereas view-source is linear, letting you view the underlying document from which your page was created, inspection is dynamic, letting you dip into a webpage to view a particular node and its associated properties. To find a node and its rules in view source, you might need to browse to several linked documents to locate the specific set of rules. Inspection locates everything for you. Of course, the inspector won’t show you the documents and their relation to each other on the server. For that, you’ll still need view-source. Further, inspection will show you live changes to the document as they occur. View-source is a moment in the life of the web page, and remains static.

Most web developers use a combination of tools outside of their browser to create attractive pages and interesting content: design and graphics tools like Illustrator and Photoshop and a broad array of content editors from Frontpage to Notepad++. For the inspector, we talked about some of the different interactions we wanted to give to developers and looked to these other programs for inspiration. The tool should feel dynamic and yet be easy to get out of the way if you want to go back to browsing the web. You should be able to quickly inspect a piece on a webpage and get as much information out of it as you wanted. Maybe you’d like to make a quick change or remove an element? Manipulate some DOM attributes, or move an element around in a page and have the Inspector make the positioning adjustments for you.

We’re not there yet. I’m still cobbling together pieces to provide some of the basics. But we’re hopeful that with these foundation blocks in place, we can start to build on them to provide unique interactions that have a more “designery” feel like the tools people already enjoy using to create content. We’re hoping the inspector will feel comfortable and intuitive to you.

Over the next little while, I’m rewriting the Tree panel, adding editing capabilities, redesigning the highlighter to look more like what’s in the mockup on the project page, adding rulers and guides to help with layout, and a few basic controls for making all of this easier to manage. The initial Style and DOM panels are waiting in the wings ready for review.

This is a different approach to inspection, for a different kind of user. We’re not looking to replace tools like Firebug and DOM Inspector – they are awesome, and we’re still totally committed to helping them be the best they can be. We think there’s a group however, that doesn’t need the depth of Firebug, but does want tools with a more “designery” feel. My hope is that Firefox and Firebug will complement each other in somewhat the same way that tools like Lightroom and Photoshop do.

To get your ideas and suggestions heard, reply here or on the dev.apps.firefox thread.

Open systems are better and lead to more productive coders. This is a wild assertion I’ll make with some cheek, mostly because I don’t think any exemplars from closed-system programming can really refute it, or will. Programmers who get into pure languages like Lisp and Smalltalk ramp up quickly and become more productive because they have full view of the system’s source code.

So too, the web.

Web-programming is often a cut and paste experience. I hear the term “cut-and-paste inheritance” used derogatorily too-often. While it’s true that in some cases, from a code-design perspective, just pasting blocks of code from one document to another can lead to a poorly-designed system, it is great for getting little pieces of code to work. It is the scientific method applied to programming. You see something that works in one place, you try copying it over and see what fails on your page. Continue.

One area where view-source breaks down is in the analysis of “what happens” with that source code. The Error Console in Firefox is a poor-excuse for a debugging mechanism and linked to the view-source window only by a hopefully connected error and a line number you can click on. Errors can come from any tab and are not necessarily associated with your code. There is no sense of iterative feedback. You have to hunt for it and usually fall into a pattern of clearing your console and reloading the page to see when the errors occur. This leads many developers to write their own logging function. Or when they’ve graduated to more advanced development, install Firebug which presents dynamic views of your source code in exciting (and sometimes surprising) ways.

Another mysterious failing of view-source is in a dynamically generated page. Something that uses document.write() or a bunch of appendChild() calls often doesn’t show correctly in view-source. A trick I learned recently to see these types of changes is to select some text and right click on it and “view-selection source”. Not exactly intuitive, but this will show you what your code generated.

I don’t think anyone can claim that view-source is a bad thing, though I have seen people try to get around it. Usually under the guise of “I have some important information or data that I need to protect”. I have seen people file bugs to add a mechanism to Firebug to prevent inspection of the underlying HTML on certain pages. I find these types of requests pretty funny, generally, and a little sad because people who think this way fundamentally don’t understand what the web is about and how it works and why it got to be the wonderful thing it is today.

It’s a fairly common practice to hide content behind a flash barrier to prevent people from getting their grubby paws on it. This creates a large swath of the web that you really have no ability to play with or learn from. Also, I think it’s fairly safe to say that learning to program in Flash is a more expensive proposition than learning to program for the web. You have to pay for tools, books and example code. If you want to make something that looks like this widget over here that has some wandering penguins on it, you have to figure it all out for yourself.

Alex mentions generative tools and libraries like GWT that create HTML and CSS styling as by-products of their execution and that these create a not-very useful rendition for view-source. This is true. Even PHP-generated HTML can be pretty disheartening to look at if you’re trying to figure out what’s going on in a web-page — its poor formatting and machine-generated constructs are not pretty to look at, but you can still sometimes glean some of the workings behind them. Having hacked around in Wordpress for a few years, understanding the way the PHP code generates a blog’s output is an interesting experiment to puzzle through. I wouldn’t have been able to do that without view-source.

Anyway, I think I’ve burbled about this enough. I love view-source. There, I’ve said it. It is one of the most valuable tools we have for understanding and learning about the web.

First, a little terminology. Feel free to skip this paragraph if you consider yourself a master of Javascript internals or compiler run-time optimization makes your skin crawl. Tracing is the mechanism Firefox’ Javascript engine (aka, “SpiderMonkey”) uses to improve code execution performance. It provides a major speedup for code running in Firefox 3.5 and up, often an order of magnitude for certain types of operations. It is the basis of the JIT or Just-in-Time compiler. Without tracing, the JS engine can’t optimize code as well, leading to significantly slower execution.

I need to be clear here: If you have Firebug installed you are probably not getting fast Javascript. Firebug doesn’t have to be active on your current page. If you have the grey icon on your status bar, you have probably disabled the JIT. This is true if you have ever enabled the Console and consequently the Script panels and left them on. This is likely true for most recent versions of Firebug. The quick fix is to disable the Script and Console panels via the mini menu on their respective tabs.

Boris Zbarsky has been doing a lot of poking around in the belly of the JS debugger lately. Working in conjunction with John Barton, they have concocted fixes for the soon-to-be-released Firebug 1.5 and Firefox 3.6. We’re working to get testable versions out as quickly as possible, but I can say that I’ve tested development builds using the pages mentioned in the bug and can verify that these fix the problem. As a side-benefit, I got to watch Boris dissect the problem through gdb in an Xterm (yes, an Xterm) and Emacs and it was pretty impressive and fun, to boot.

When installing Firebug one of the first things most people do is enable the Console. It’s such a useful debugging tool. I myself have been using Firebug for over a year without JITted code. I probably never noticed the slowdown simply because I’m so used to running my browser this way and have pretty fast machines. After disabling the Console and Script panels there are a few pages that just load much much quicker. It’s kind of shocking.

Since the patch has landed on Firefox 3.6, I’m expecting either a beta or release candidate of that to come out shortly. I’m also hoping for another Firebug beta (or release candidate) later this week. In the meantime, if you’re not using them, I recommend disabling the Console and Script panels and find out what you’ve been missing and turn them on only as-needed. This will likely be the work-around for Firefox 3.5 users unless we decide to push this back to that branch but I have my doubts that this is something we would do.

Improved Net Panel accuracy

One of the problems with Firebug’s Net panel in the past has been inaccurate timings. Because Firebug is entirely written in JavaScript some network and UI activity could block Firebug during long operations and cause the timings displayed there to be less than accurate. This has finally been corrected with the landing of a new service called the http-activity-distributor. For more details on the implementation and use of the newly-improved Net panel, see Honza’s blog post on the topic.

New Break Functionality

In Firebug 1.4, we introduced the concept of “break-on-next” to the Script panel. This was a “pause” button sitting between the inspect icon and the Console tab. In 1.5, we’ve extended this concept to the Console, HTML and Net panels to allow more exciting types of breaks.

In the Console, we’ve replaced the mini-menu Break-on-Errors option with the pause button. The reasons for this possibly contentious change was it made for a more consistent use of menus and the break button. Now, to enable Break on Errors, select the Console panel and hit the pause button. You’ll see that familiar glow to indicate that it’s waiting for an error. Now whenever an error occurs on the page, you’ll be dropped into the script panel at the line where the error occurred.

The HTML panel’s break button is a little different. This is the Break-on-Mutation feature. When this is enabled, whenever a bit of JavaScript modifies an HTML element, you’ll be taken to the Script panel and the modifying code while be highlighted. Related to this, you should be able to see modified HTML occurring in real-time in the HTML panel with affected elements and attributes being highlighted as they change in the page.

Finally in the Net panel, the break button acts as a Break-on-XHR button. This is intended to help debug AJAX apps by allowing you to halt the debugger during an XmlHttpRequest send. As in the other break types, you’ll be transported to the script panel when an XHR object fires off its request and you’ll be given the option to copy the message.

John Barton and Honza have written a great interactive demo page describing these new features on getfirebug.com.

Mixed Development

• We made a few tweaks to the UI in this version. We replaced the “Off” label with a single “power” button (or window close button on Mac) as promised during the last release.

• Kevin Decker added the search panel originally intended for version 1.4 with some nice options

• Persist option on Console and Net Panel. Save your data!

• Improvements to the Inspector.

Still more to come. Between now and final release we plan on hunting down a few more bugs to make this even more stable. Feel free to download and give it a try.

Now for version 3.6b3 and above, you’ll have to set a per-application version in about:config that looks like this:

See Mossop’s post on the topic for the deep story.

As in the previous poll, I added a Junk column for responses that didn’t really make sense. “I <3 Firebug!” is great to hear (and Firebug <3s you too!) but it wasn’t really useful for the purposes of this poll. Augmenting this column, I created another category for responses lamenting Firebug stability or specific missing features. This was tied for first place with the most votes.

The Winners

Third place – Tie!

• Search feature
• Console. Surprised some people dislike the Console, but two of you did. One person mentioned a lot of exceptions coming from the browser showing up in the Console lowering the quality of information. These can often be cut down by unchecking the “Show Chrome Errors” and messages options in the Console’s mini-menu.

Second place – Tie!

These have the dubious distinction of having the same number of responses as the Junk column.

• CSS panel
• DOM panel
• Profiler

First Place

• Script panel — Responses varied from “I don’t know how to use breakpoints” to users who prefer using the Console to do printf-style interactive debugging. Other respondents claimed the script panel was just too buggy.

caveat: I believe there is probably more than one type of user of Firebug. Some of them may not be using Twitter and this poll might not have gotten to them. The types of users who replied and said that their favorite feature was the HTML Inspector and live-editing of CSS are probably the same group of people who don’t make heavy use of the Script debugger. If you’re a heavy debugger, please let us know in the comments.

Honorable Mentions

• HTML node editor – If you double click on a tag in the HTML view, you’ll see the node editor. Clicking the “Edit” button or using the Escape key will get you out of it.
• Event logging – right click on a node in the HTML viewer and select “Log Events”. Now every mousemove, click and keystroke in that node will be registered in the Console. How can you not love that?

There were no votes(!) for the Net panel, so everyone clearly loves it and thinks it’s awesome.

Take Aways

• we need to work harder on bugfixes and stability. Spending a lot of effort on stability and usability would probably go a long way towards making Firebug a better, more pleasurable to use piece of software.

• The CSS and DOM tabs aren’t loved. Adding better navigation to the DOM page, or reworking it entirely might be useful. Getting rid of it and the CSS tab entirely could be another option but not one we’d consider doing without some very strong feedback from the community.

• The Profiler ties in with the Script panel pretty closely. If you’re not doing heavy JS debugging, you might not need the profiler. It’s a pretty special-purpose tool to measure a page’s JavaScript performance.

• Search feature was a bit of a surprise, but we’re improving that for version 1.5 so hopefully it becomes easier to use.

As before, please leave us your comments if you think we’re missing something.

The break-down in exploding 3D pie chart format shows that 55% of users call the Inspector their hands-down favorite feature. In reality, this is probably closer to 73% if you combine the HTML tab which 18% reported as their favorite. When most people think “inspect” or “html” the next feature they describe is “being able to modify the CSS or see the layout of that node in the HTML panel”.

The next favorite feature is a tie between the Net panel and the Console. It’s possible that since I first collected the responses that the tie has been broken, but certainly not by much, and probably not within a suitable margin for error. The remaining 9% of responses were incomprehensible internet sounds. The cosmic background static of emerging consciousness.

How does this help? Well, it certainly tells us where we need to focus our efforts. We have seen a few errors with the Inspector over the past couple of years and think in version 1.5, we’re going to have most of them fixed. Annoying highlighter offsets and weird z-index issues should be a thing of the past thanks to work by contributor Mike Ratcliffe who came to us through the Firebug lite project.

I’m going to follow-up a bit later with the results of the “least favorite feature” question. They’re a bit harder to make sense of as the answers weren’t quite as obviously clear. Please let us know if this pie chart matches (or doesn’t) what you think is your favorite feature, too. This isn’t the end of the question — we’re just getting started.

Honza wrote a good introduction to the new activation model awhile back and you may find it useful to understand the differences between activation mechanisms in 1.3 and 1.4.

JJB writes: “Firebug 1.4 is a true community achievement. We have had contributions from many developers and a few designers, with additions both large and small.”

And it’s true. We’ve seen contributions from several new people over the past year and some long-standing issues fixed. Kevin Decker, creator of the nascent FireDiff extension for Firebug contributed a new multi-file search capability. Hans Hillen working with the Paciello Group has done a tremendous job of making the Firebug UI accessible to screen readers. He also added a new Customize (keyboard) Shortcuts preferences pane (available from the Firebug menu).

You should also see some new icons in the Windows version of Firebug. Austin Andrews (aka Templarian) in IRC modified some of the Silk icons from FamFamFam for inclusion in Firebug. Some improved debugger icons have made it into the Mac and Linux versions as well. We still need to do some tweaking of the Mac skin so, if you or anyone you know would like to help out, get in touch with us.

oh, and that “Off” label on the right of the panel is a temporary thing to introduce people upgrading from 1.3 to the new behavior of the panel control icons (minimize, detach and close/off).

Over the next week or so we’re going to be writing more about the new features in Firebug 1.4 and how to use them.

Hats off to the Firebug developers and to all the great testers and users who helped us through the alpha and beta stages. We couldn’t have done it without you.

photo by Mike McCaffrey via Flickr. Thanks!