Introducing Detector: Combining Browser- & Feature-Detection for Your Web App

Feb. 21, 2012: v0.5 of Detector was pushed out. Read about the new features.

Feb. 27, 2012: A small update, v0.5.1, was made to Detector to clean up PHP Notices as well as add two methods to push Detector data to the browser so the data can be used a la Modernizr.

With the initial release of Yiibu's ProfileDetector is already YABFDL (Yet Another Browser- and Feature-Detection Library). The main question behind Detector, "How does one go about *intelligently combining browser- and feature-detection into one package?*," has been floating around in my head ever since I heard Yiibu's talk, Adaptation. Because of two recent events, our holiday card project and the OpenDDR/WURFL/ScientiaMobile kerfuffle, I decided to finally tackle that question and see what I could come up with to answer it.

Introducing Detector

Detector (demo & code)  is a simple, PHP- and JavaScript-based browser- and feature-detection library that is still in its infancy. Detector gives server-side developers information about what types of devices may be requesting their content as well as the HTML5 & CSS3 features a requesting browser on that device may or may not support. With Detector a developer can serve the appropriate markup, stylesheets, and JavaScript to a requesting browser without being completely dependent on a browser-detection library being up-to-date nor completely dependent on a front-end-only script loader. Detector is based on Modernizrmodernizr-server, and the browser-detection library from Mobile Web OSP. It also benefits from a healthy dose of inspiration from Yiibu's Profile. Want more of the gory, technical details? Check out the README for more information.

Why Create Detector?

With Yiibu's Profile, Luke Wroblewski's (@lukew) article, "RESS: Responsive Design + Server Side Components," and the Future Friendly movement I think that more and more folks are accepting that server-side technologies still have a large part to play in delivering mobile-optimized solutions. That being said, browser-detection cheerleaders like myself can learn a thing or two from the responsive design/feature-detection folks. Detector was created as a way of, hopefully, combining the best of both browser- and feature-detection and giving server-side developers a lot of power and flexibility in developing cross-browser, as well as mobile, solutions.

Flexible & Future Friendly

I wanted to address two primary goals when developing Detector. The first goal was to create a solution that was forward looking and could adapt to new devices and browsers on its own. I didn't want a developer to have to worry that their website might break if a new a browser came out with a different user-agent than those already being tracked. This is one of the real strengths of using feature-detection as a solution. A feature is either available or it isn't. The first time Detector gets a visit from a new user-agent string it tests that browser for all of its available features and saves that profile to disk for future use with other browsers with that same user-agent. In this way Detector can grow and adapt to changes in the browser & mobile landscape. Also, because Modernizr (and it's long list of pre-built tests) serves as the core feature-detection library of Detector a developer can add and track their own tests just by using the Modernizer.addTest() plug-in API.

Open Browser & Device Knowledge

My second goal was to see if I could find a way to capture and share device knowledge. While Detector is focused on browser knowledge as opposed to device knowledge I think the information is still useful overall. Especially to web developers who are, for the most part, only ever going to interact with the browser anyway. I feel very strongly that their should be a central, open resource for developers to rely upon to not only learn what browsers support what features but a way to use that data within their applications. Because of that I have signed onto the Open Device Knowledge Collaborative. Detector is not nearly stable enough to help create that resource now but I do hope that it can in the future. At some point I will create a central repository of browser profiles that anyone can use in their applications (with or without Detector!) and, via Git, developers will be able to submit their own profiles back to the central repository for others to use. It's an ambitious idea and their are a lot of hurdles yet to overcome but I do think it's an important goal for Detector and the community at large.

Where Detector is Going

Detector is far from perfect as a solution. As I said, it's in its infancy. I'd love to see the following get addressed:

  • New profiles could contain bad data that, in its current incarnation, wouldn't get updated by more "reliable" browser visits in the future. Basically, is there a sampling and/or confidence metrics that could be used to re-test browsers?
  • Modernizr-based media query tests seem to be really flaky and it's obviously a problem with Detector itself. When I use the media queries outside of Detector they work as expected.
  • Versioning of profiles as well as creating that central repository so profiles can be used by anyone.
  • Most importantly, Detector needs more browsers to use it to really test its capabilities and accuracy.

While it is still early days for Detector hopefully lessons can be learned from its implementation for others developing similar solutions.

Helping Me Test Detector

If you can, please hit the Detector demo ( on, preferably, your mobile device of choice and see if Detector works as expected. If it doesn't please shoot me a note from the contact link under the Browser Profile information.

*[YABFDL]: Yet Another Browser- and Feature-Detection Library

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