Release Notes for Safari Technology Preview 💯

Safari Technology Preview Release 100 is now available for download for macOS Catalina and macOS Mojave. If you already have Safari Technology Preview installed, you can update in the Software Update pane of System Preferences on macOS.

This release covers WebKit revisions 254696-255473.

Web Inspector

  • Added links to Web Inspector Reference documentation (r254730)
  • Renamed the Canvas Tab to be the Graphics Tab, and included basic information and graphical representations of all Web Animation objects that exist in the inspected page (r255396)
  • Allowed developers to evaluate arbitrary JavaScript in isolated worlds created by Safari App Extensions via the execution context picker in the Console (r255191)

Web Animations

  • Added support for the options parameter to getAnimations() (r255149)
  • Changed animations to run accelerated even if other animations targeting the same element are not accelerated (r255383)
  • Fixed changing the delay of an accelerated animation to correctly seek (r255422)
  • Fixed a leak of CSS Animations when removing its animation-name property (r255371)
  • Separated setting a timeline’s current time from updating its animations (r255260)
  • Updated all DocumentTimeline objects when updating animations (r255141)


  • Fixed User Verification (UV) option present on a CTAP2 authenticatorMakeCredential while the authenticator has not advertised support for it (r254710)


  • Added support for allow="fullscreen" feature policy (r255162)
  • Changed EME to only emit an array of persistent-usage-records when more than one record is discovered (r254896)
  • Corrected VTT Cue Style handling to match the specification (r255151, r255227)
  • Fixed decoder glitches when watching videos on (r254761)
  • Fixed AirPlay placard not visible when AirPlay is entered in fullscreen mode (r255103)
  • Fixed video sound sometimes continuing to play in page cache (r254814)
  • Fixed HTMLMediaElement to not remove the media session at DOM suspension time (r255116)


  • Added finite timeout when synchronously terminating a service worker (r254706)
  • Fixed :matches() to correctly combine with pseudo elements (r255059)
  • Fixed automatic link replacement via “Smart links” to emit insertLink input events (r254945)
  • Disabled Service Workers before terminating an unresponsive service worker process (r255438)
  • Implemented “create a potential-CORS request” (r254821)
  • Implemented transferable property of OffscreenCanvas (r255315)
  • Improved performance speed of index records deletion in IndexedDB (r255318)
  • Made pasteboard markup sanitization more robust (r254800)
  • Used Visible Position to calculate Positions for highlights (r254785)


  • Fixed EXIF orientation ignored for some CSS images (r254841)
  • Fixed elements no longer stay fixed with elastic overscroll (r255037)


  • Added support for MediaRecorder.requestData (r255085)


  • Fixed DateMath to accept more ISO-8601 timezone designators even if they are not included in ECMA262 to produce expected results in the wild code (r254939)


  • Implemented sub-source texImage2D and texSubImage2D (r255316)