Firefox 98 for developers

This article provides information about the changes in Firefox 98 that affect developers. Firefox 98 was released on March 8, 2022.

Changes for web developers


  • The HTML <dialog> element is now available by default. This element and its associated DOM APIs provide support for HTML-based modal dialog boxes (bug 1733536).



No notable changes




  • The deprecated WebVR API is now disabled by default on all builds (previously it was enabled on Windows, macOS, and all nightly/dev builds). It can be re-enabled in about:config by setting dom.vr.enabled to true (bug 1750902).

WebDriver conformance (Marionette)

  • Improved initial page load checks for newly opened tabs (bug 1747359).

Changes for add-on developers

  • Web extensions using webRequest were started early during Firefox startup. This has changed to only trigger early start-up for extensions using webRequest blocking calls. Non-blocking calls no longer cause the early startup of an extension. (bug 1749871)
  • cookieStoreId added to userScripts.register. This enables extensions to register container-specific user scripts (bug 1738567).

Older versions