Firefox Quantum made Firefox fast again, but speed is only part of the story. A ton of work has gone into making Firefox an exceptional tool for creating on the Web. Let’s dive into the changes coming in Firefox 58, currently available to preview in Firefox Developer Edition.
More Control for CSS Authors
Try it yourself on this CodePen by Chris Coyier.
We’ve also implemented the CSS
font-display property, allowing authors to specify how long the browser should wait for a web font, and when it should consider swapping in a font once it’s loaded.
Firefox Quantum also introduced a brand new CSS engine (“Quantum CSS”) which fixed numerous bugs and inconsistencies with CSS in Firefox. For example,
calc() now works everywhere that the spec says it should.
An Even Better Debugger
We’ve implemented tons of new features during the rewrite, but the debugger deserves special mention. First, source maps finally work everywhere, and even include proper syntax highlighting for markup like JSX:
The best way to discover the new DevTools is to download Developer Edition and try them yourself.
WebVR, FLAC, and Other Tidbits
Firefox is driving new, fundamental capabilities of the Web. Firefox 55 introduced support for WebVR on Windows, and included experimental support for macOS. With Firefox 58, WebVR now is supported by default on both Windows and macOS.
If you’re interested in creating virtual reality experiences on the Web, check out the A-Frame library, or read our article on how Firefox Quantum delivers smooth WebVR performance at 90 fps.
In other firsts, Firefox 51 was the first browser to support FLAC, a lossless audio format, on the Web. Until now, this support was limited to Firefox on desktop platforms (Windows, macOS, and Linux), but Firefox 58 brings FLAC support to Android. That means that Firefox, Chrome, and Edge all support FLAC on every platform but iOS.
We also landed a few changes to help measure and improve Firefox’s performance:
PerformanceNavigationTimingAPI provides access to performance metrics related to page loading.
- Off Main Thread Painting (“OMTP”) has been enabled by default on Windows, which improves Firefox’s responsiveness by reducing the workload on the main thread.
- We’ve enabled budget-based background timeout throttling which slows down scripts running in background tabs to save further CPU resources.
Lastly, Content Security Policies (CSPs) now support the
WebExtension API Additions
- Access brand new website privacy controls like first-party isolation and fingerprinting resistance, added as part of the ongoing Tor Uplift.
- Toggle, observe, and control whether or not a tab is displayed in Reader Mode.
- Query and observe changes to the browser theme, making it possible for add-ons to adapt themselves to fit in with arbitrary themes.
We’re currently planning additional WebExtension capabilities for 2018, including looking into possibilities for hiding individual tabs, or the entire tab bar.
About Dan Callahan
Engineer with Mozilla Developer Relations, former Mozilla Persona developer.