Mozilla ramps up Manifest V3 support in Firefox

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Mozilla continues to increase Manifest V3 (MV3) support for add-on developers, with recent Firefox releases introducing key improvements aimed at enhancing Chrome compatibility and user experience.

Building upon previous work in Firefox 126, the release of Firefox 127 this week brought several notable enhancements.

One significant update involves keyboard shortcuts for extensions.

“Customised keyboard shortcuts associated with the executebrowser_action command for MV2 extensions will be automatically associated with the executeaction command when migrating the same extension to MV3,” the company explained. This change ensures that users migrating from Manifest V2 (MV2) to MV3 will not experience disruptions in their familiar shortcut functionalities.

Additionally, Mozilla has expanded the capabilities of the declarativeNetRequest API.

“declarativeNetRequest getDynamicRules and getSessonRules API methods now accept the additional ruleIds filter as a parameter and the rule limits have been increased to match the limits enforced by other browsers,” explained Mozilla. This move brings Firefox’s implementation more in line with other major browsers, facilitating easier cross-browser development.

Notably, this release will also mark a milestone for mobile users as MV3 will be supported on Firefox for Android.

Amid these changes, Mozilla has reaffirmed its commitment to supporting existing technologies.

“The webRequest API is not on a deprecation path in Firefox,” the company stated, addressing concerns about the future of this widely-used API.

Furthermore, Mozilla emphasised, “Mozilla has no plans to deprecate MV2,” providing reassurance to developers who may not be ready to transition their extensions.

Looking ahead, Firefox 128 is set to introduce further Chrome compatibility enhancements and other MV3 improvements. Mozilla invites feedback from developers via email.

For add-on developers looking to adopt MV3, Mozilla recommends referring to their comprehensive migration guide.

As browser extensions continue to play a crucial role in personalising the web experience, Mozilla’s ongoing efforts to support MV3 while maintaining backward compatibility underscore its commitment to both innovation and user choice.

(Photo by Fuu J)

See also: SlashData: Rust sees fastest growth, JavaScript still dominates

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One comment on “Mozilla ramps up Manifest V3 support in Firefox

  1. Daniel Max on

    It provides a clear update on Mozilla’s ongoing support for Manifest V3 (MV3) and its efforts to enhance compatibility with Chrome. The improvements in Firefox 127, particularly around keyboard shortcuts and the declarativeNetRequest API, are well-explained and show Mozilla’s dedication to easing the transition for developers. It’s also reassuring to read that Mozilla is committed to maintaining support for MV2 and the webRequest API. The inclusion of MV3 support for Firefox on Android is a significant milestone. Overall, this piece offers valuable insights for developers and highlights Mozilla’s balanced approach to innovation and user choice. Well done!


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