Thomas Fuchs
Hi, I'm Thomas Fuchs. I'm the author of Zepto.js, of, and I'm a Ruby on Rails core alumnus. With Amy Hoy I'm building cheerful software, like Noko Time Tracking and Every Time Zone and write books like
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Why I use Safari for Development

July 9th, 2009

For web developers, there’s an obvious choice of which browser to use for developing web applications. Firefox it is, right? Wrong.

Standards, schmandards

Let’s compare the two browsers, more specifically Safari 4 vs. Firefox 3.5. Both browsers pass the Acid2 test with flying colors, but when it comes to Acid3, Firefox only reaches 93% compliance (up from 71% in Firefox 3.0). Safari? 100%.

Acid3 on Safari 4

That’s a pretty good start for Safari. Basically, if some HTML/CSS works on Safari, the chances are very high it will work on Firefox 2 and higher, and on IE 6 and higher (with minor tweaks).

Development tools

Firefox comes with no development tools, but it’s easy to install Firebug, the de-facto industry standard for HTML inspection, CSS munging and JavaScript debugging. But Firebug has been haunted by bugs lately, and the new 1.4 series is still in beta. Moreover, it feels a bit tacked-on and sometimes just fails to work or becomes unresponsive, or slows things down (hopefully this will be resolved in the 1.4 final, overall Firebug was one of the awesomest things ever for web developers, and I don’t ever want to go back to the days of alerts).

Firebug 1.4 beta network panel

On the plus side, there’s some really great additional plugins like YSlow and I tend to use those independently of the main development cycle, as these tools are more for deployment optimization anyway, so they don’t really play into the development of the web app as such.

Safari 4 Resources Panel

Safari comes with everything you need installed, and the tools themselves are very stable. And they even look nice, which makes debugging less of a drama. I especially like the Profiler, which has features not found in Firebug that come in really handy if you’re doing advanced JavaScript. The tools are very well integrated and are part of the application instead of an add-on, which also means they can access the browser/network data on a deeper level then Firebug can.

Safari Console Autocomplete

The console in Safari has some nifty features, foremost a well-working autocomplete implementation. Firefox has autocomplete too, but doesn’t show you the current option until after you hit .

The user interface is much more streamlined and cleaned up on Safari as well. The only gripe I have is that I’m not in love with the font the console and debugger on Safari uses (but I’m a font nerd).


And important (for me!) distinction between the two browsers is that Firefox messes with your JavaScript by doing a pre-optimization step on declaration. This means that:

function x(a){ 
  return 1*2; 

will be automatically converted into

function x(a){ 
  return 2; 

This change is not internal– if you to a x.toString() on the function source code actually has changed. I’m not very much in love with this automatic optimization step– I’d rather see this done by some kind of external tool, like the YUI Compressor, which does some of these microoptimizations. Neither Safari, nor Chrome or IE does that.

Quick, fix that bug!

I’ve done several bug reports to the WebKit project over the years, and all of them where eventually adressed (in big projects like this, it can be expected that non-critical issues might take a while to be resolved). On Firefox, there’s been certain bugs that have a long history of developer hairpulling and nailbiting. Here’s my favourite (Quote: “This bug reveals a problem in Mozilla post-release bug fixing. We have been made to wait 6 years for this bug to be fixed.”).

Note that I’m sure that the people working on the Firefox development team are working very hard (I know some of the awesome people who worked there!), and it’s more of a management issue.


I used Firefox since version 1.0 for my web development, but I’ve switched over to Safari for 99% of my development needs. I only go back to Firefox to make sure it works there and for some of the plugins.

Btw, I know that there are operating systems other than OS X out there. But I’m not using them for development, for several reasons, one of them being that OS X is the only system that allows me to test all major browsers side-by-side by means of virtualization software (I run IE6/7/8 in VMs), and have a Firefox on Linux VM, too. And the iPhone Simulator that comes with XCode runs only the Mac, of course. If you’re serious about front-end web development, there’s pretty much only one OS choice (Let the flamewars begin!).