Developers from Mozilla updated about their plans regarding support for the second and third versions of the Chrome manifest in Firefox. Google announced that starting in June, they will stop supporting the second version of the manifest in test releases Chrome 127 (DEV, Canary, and Beta), with support in stable branches expected to end no earlier than July.
On the other hand, Mozilla has decided to continue supporting the second version of the manifest for the foreseeable future. They will take advantage of the opportunities available in the third version of the manifest to introduce new additions, ensuring full compatibility in Firefox. Firefox will retain full-fledged API Webrequest support while Chrome will shift to a reading mode.
In Firefox, background scripts will use event pages to execute based on the DOM, unlike in the third version of the manifest where Service Workers are required. Although Firefox does not yet support background scripts based on Service Workers, developers will have the option to transition their Event Pages and scripts to Service Workers to create additions compatible with both Chrome and Firefox.
The Chrome manifesto defines capabilities and resources for extensions developed using the Webextensions API. Since Firefox version 57, the browser has fully transitioned to using API Webextensions and discontinued support for XUL technology. This move has facilitated the development and portability of extensions across various web browsers, ensuring compatibility with the second version of the Chrome manifest.
Google’s introduction of the third version of the manifest aims to simplify the creation of secure and efficient extensions, while restricting the creation of unsafe and sluggish ones. The dissatisfaction with the third version lies in the restriction of the Webrequest API to a read-only mode, replacing it with the limited declarativeNetrequest API that imposes rules preventing the use of custom filtering algorithms.