Firefox 98 for 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 (Firefox bug 1733536).

• The hyphenate-character property sets a string that is used instead of a hyphen character (-) at the end of a hyphenation line break (Firefox bug 1751024).

No notable changes

• navigator.registerProtocolHandler() can now register protocol handlers for the ftp, sftp, and ftps schemes (Firefox bug 1705202).

DOM

• HTMLElement.outerText is now supported (Firefox bug 1709790).
• The properties colorSpaceConversion, resizeWidth and resizeHeight can be passed to the method Window.createImageBitmap() and WorkerGlobalScope.createImageBitmap() using the options object (Firefox bug 1748868 and Firefox bug 1733559).
• ElementInternals now has new form-associated custom element methods and properties that allow custom elements to interact with a form. These include the form, labels and willValidate properties, and the setFormValue() method. (Firefox bug 1556362, Firefox bug 1556373, Firefox bug 1556365, Firefox bug 1556449).

Removals

• 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 (Firefox bug 1750902).

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

• 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. (Firefox bug 1749871)
• cookieStoreId added to userScripts.register. This enables extensions to register container-specific user scripts (Firefox bug 1738567).