Chrome dev tools

November 30, 2009 5:23 pm | 2 Comments

I just finished reading the latest post on the Chromium Blog: An Update for Google Chrome’s Developer Tools. Dynatrace’s Ajax Edition was impressive – just take a look at what John Resig had to say. I’m also impressed by what’s been added to WebKit’s Web Inspector and Chrome’s dev tools. You should definitely take them for a spin, but I’ll give you a preview here.

A key part to any tool’s success is the assurance that there’s support behind it in the way of documentation, tutorials, issue tracking, etc. This blog post links to the new chrome dev tools site that has been put together, including several video tutorials. I spent most of my time walking through the full tutorial. To see these new tools, make sure to get on the Chrome dev channel. Finally, any issues can be seen and added via the chromium issues page.

Once you’ve got the latest Chrome dev release, you can access these tools by clicking on the Page menu () and select Developer -> Developer Tools. There are six panels to choose from. The Elements panel shows the DOM tree. A nice feature here is the ability to see the event listeners, including anonymous functions, attached to any element.

Much of my time analyzing web sites is spent looking at HTTP waterfall charts. This is captured in the Resources panel. Since this slows down web sites, it’s off by default. You can make it enabled permanently or for the current session. Doing so reloads the current web page automatically so you can see the HTTP waterfall chart. The DOMContentLoaded and Onload events are shown (blue and red vertical lines respectively). This is incredibly helpful for developers who are tuning their page for faster performance, so they can confirm deferred actions are happening at the right time. The only other tool I know that does this is Firebug’s Net panel.

JavaScript debugging has gotten some major enhancements including conditional breakpoints and watch expressions.

Developers can finally get insight into where their page’s load time is being spent by looking at the Timeline panel. In order to get timeline stats, you have to start and stop profiling by clicking on the round dot in the status bar at the bottom. The overall page load sequence is broken up into time segments spent on loading, JavaScript execution, and rendering.

The most differentiating features show up in the Profiles panel. Here, you can track CPU and memory (heap) stats. A couple other tools track CPU, but this is the only tool I’m aware of that tracks heap for each type of constructor.

Most of these features are part of WebKit’s Web Inspector. The new features added by the Chrome team are the timeline and heap panels. All of these improvements have arrived in the last month, and result in a tool that any web developer will find useful, especially for building even faster web sites.