Firefox 42 has arrived! In this release, we put a lot of effort into the quality and polish of the Developer Edition browser. Although many of the bugs resolved this release don’t feature in the Release Notes, these small fixes make the tools faster and more stable. But there’s still a lot to report, including a major change to how Firefox works.
Debugging over wifi
Now, with remote website debugging, you can debug Firefox for Android devices over wifi – no USB cable or ADB needed.
Multiprocess is enabled by default
Multiprocess Firefox (aka E10s) has been enabled by default in Developer Edition. When it’s enabled, Firefox renders and executes web-related content in a single background content process. If you experience any issues with addons after updating to Developer Edition 42, try disabling incompatible addons or reverting to a single process mode using about:preferences.
Windows 10 theme support
The Developer Edition theme has a new look in Windows 10 to match the OS styling. Take a look:
React Developer Tools support for Firefox
If you’re developing with ReactJS, you may have noticed that the React project recently released a beta for their developer tools extension, including initial support for Firefox. While there are no official builds yet of the Firefox version, the source is available on github.
Other notable changes
- Asynchronous call stacks now allow you to follow the code flow through setTimeout, DOM event handlers, and Promise handlers. (Bug 981514)
- There is a new configurable Firefox OS simulator page in WebIDE. From here, you can change a simulator to run with a custom profile and screen size, using a list of presets from reference devices. (Bug 1156834)
- CSS filter presets are now available in the inspector. (Bug 1153184)
- The MDN tooltip now uses syntax highlighting for code samples. (Bug 1154469)
- When using the “copy” keyboard shortcut in the inspector, the outerHTML of the selected node is now copied onto the clipboard. (Bug 968241)
- New UX improvements have landed in the style editor’s search feature. (Bug 1159001, Bug 1153474)
- CSS variables are now treated as normal declarations in the inspector. (Bug 1142206)
- CSS autocomplete popup now supports pressing ‘down’ to list all results in an empty value field (Bug 1142206)
Thanks to everyone who contributed time and energy to help the DevTools team in this release of Firefox Developer Edition 42! Each release takes a lot of effort from people writing patches, testing, documenting, reporting bugs, sending feedback, discussing features, etc. You can help set our priorities by sharing constructive feedback and letting us know what you’d like from Firefox Developer Tools.
You can download Firefox Developer Edition now, for free.
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