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Safari Technology Preview 120 Release Offers Bug Fixes and Performance Improvements

Safari Technology Preview 120 Release Offers Bug Fixes and Performance Improvements

Apple on Thursday released Safari Technology Preview 120, the latest version of their developer preview web browser. The preview version of Apple’s popular browser offers developers and other interested users the ability to try out features that may or may not, debut in future public release versions of Safari.

‌Safari Technology Preview‌ release 120 brings bug fixes and performance improvements for Web Inspector, Scrolling, CSS, JavaScript, Web API, Media, WebRTC, Web Audio, Accessibility, Payment Request, Speech Recognition, and Private Click Measurement.

The current ‌Safari Technology Preview‌ release is built on the new Safari 14 update included in macOS Big Sur.

The preview is available for both macOS Catalina and macOS Big Sur.

Release 120

Web Inspector

  • Elements
    • RTL content inside elements is reversed and unreadable (r271458)
    • Font details sidebar panel
      • Improved line wrapping of table row titles (r271528)
      • Updated fractional variation axis ranges and default values to not be rounded (r271620)
      • Changed the “Historical Figures” section name to “Alternate Glyphs” (r271612)
  • Sources
    • Allowed breakpoint actions to be evaluated as a user gesture (r271373)
  • Console
    • Fixed bidi confusion when evaluation result has RTL text (r271726)


  • Changed slow-scrolling reasons to not propagate across frame boundaries (r271508)
  • Fixed scroll-chaining to trigger before the complete end of overscroll (r271730)
  • Fixed scroll-padding to affect paging operations (r271788)
  • Fixed scroll-snap points to be triggered during programmatic scroll (r271439)


  • Added relayout for grid items when definiteness changes (r271745)
  • Fixed incorrect scroll-snap-align parsing (r271480)
  • Handled shapeMargin becoming NaN (r271738)
  • Implemented logical border-radius (r271447)
  • Included aspect-ratio in percentage resolution (r271375)
  • Supported transferred min/max block size for aspect-ratio (r271554r271648)
  • Optimized :hover and :active style invalidation for deep trees and descendant selectors (r271584)
  • Updated font when resolving letter-spacing: calc(…) values (r271688)
  • Reversed transform animation not applied alongside other transform animations (r271524)


  • Fixed super accesses on arrow functions defined as a class field (r271420)


  • Accelerated HTMLInputElement creation (r271672)
  • Changed to use the event loop to set the page title (r271514)
  • Changed a non-integer tabindex to match the element behavior as if the tabindex was omitted (r271523)
  • Disabled the context menu item and menu bar item to toggle automatic spelling correction where autocorrect=”off” (r271459)
  • Fixed elements in a table getting incorrectly selected in JavaScript (r271635)
  • Included an origin identifier when writing promised image data to the drag pasteboard (r271685)


  • A video element needs to ignore the request to enter/exit fullscreen before the current fullscreen mode change is completed (r271377)
  • Allowed MediaStream and non MediaStream backed videos to play together (r271698)
  • Changed to prevent two pages in the same process to not play media stream backed video elements at the same time (r271670)
  • Fixed videos not playing on Facebook Stories (r271725)
  • Fixed picture-in-picture video subtitles that stop updating when Safari is backgrounded (r271737)
  • Fixed playback failure on marketwatch.com (r271531)
  • Fixed Netflix controls to correctly fade out after entering fullscreen (r271656)
  • Fixed Facebook pausing video in picture-in-picture during scroll (r271470)
  • Introduced a MediaSessionGroupIdentifier (r271643)
  • Updated buttons of the media permission prompt (r271485)


  • Enabled WebRTC VP9 profile 0 by default (r271641)
  • Disabled verification timer in case of capture suspension (r271749)
  • Changed to notify capture state immediately on page close (r271640)

Web Audio

  • Addressed WebRTC live Opus audio stream stutters (r271575)


  • Implemented aria-braillelabel and aria-brailleroledescription (r271416)
  • Fixed AT-synthesized key events for common user actions such as increment or decrement (r271760r271536)

Payment Request

  • Changed to use the first item in shippingOptions even when it’s not selected (r271735)
  • Fixed constructor to throw an error if the same payment method is provided more than once (r271734)
  • Fixed issue where the shippingOption of the PaymentResponse is null after updateWith (r271703)

Speech Recognition

  • Made SpeechRecognition permission error more informative (r271381)
  • Updated media state for active speech recognition as it uses audio capture (r271636)

Private Click Measurement

  • Enabled output logs by default, including to Web Inspector (r271473)

Bug fixes

  • Fixed “Blocked Plug-in” instead of showing a PDF (r271650)
  • Fixed combinations of nested perspective and transforms causing blurry layers on retina displays (r271388)
  • Fixed SVG reference filter chain with errors applying only some of the filters and producing incorrect output (r271785)
  • Removed explicit clamp to SRGB for Lab colors on CG platforms that support wide color (r271712)

While the preview is intended for use by developers and advanced users, in order to provide Apple with feedback on the development of the Safari browser, it can be run side-by-side with the release version of Safari. The app doesn’t require a developer account to download and install. For more information, visit the Safari Technology Preview website.