Release Notes for Safari Technology Preview 55

Safari Technology Preview Release 55 is now available for download for macOS Sierra and macOS High Sierra. If you already have Safari Technology Preview installed, you can update from the Mac App Store’s Updates tab. This release covers WebKit revisions 230521-230913.


  • Added support for calc() in webkit-gradient and cross-fade (r230816)
  • Changed :active pseudo class to deactivate when using pressure sensitive trackpad (r230786)
  • Omitted the default value when serializing font-feature-settings (r230838)
  • Updated HSL and HSLA parsing to match CSS Color 4 (r230861)


  • Enforced content-type for <script> tags (r230602)
  • Fixed input.webkitEntries to work as expected when a folder contains accented chars (r230639)
  • Setting event.returnValue to true is now a no-op (r230664)


  • Fixed animated GIFs with finite looping to loop the expected number of times (r230712)
  • Fixed the position of the caret in empty table cells (r230797)


  • Added the accessibility events to the HTML attribute names so AOM works with DOM Level 1 events (r230890)
  • Fixed a hang when triggering an alert from an AOM increment event (r230782)


  • Fixed function.prototype.caller to not return generator bodies (r230662)

Web Driver

  • Fixed simulated mouse interactions to not be done until the associated DOM events have been dispatched (r230817)

Web Inspector

  • Fixed selecting and copying text from a Network tab popover (r230701)


  • Added allSamplesInTrackEnqueued event (r230909)


  • Fixed a WebRTC data channel issue for non-ASCII characters. (r230524)


  • Changed to use CSP and content blockers for sync XHR (r230810)

Bug Fixes

  • Fixed an issue that would sometimes incorrectly rule out PDF as a mime type that can be showed (r230853)
  • Fixed an issue with Command-clicking web app links on (r230721)