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Apple Releases Safari Technology Preview 144 Release Offers Bug Fixes and Performance Improvements

Apple Releases Safari Technology Preview 144 Release Offers Bug Fixes and Performance Improvements

Apple on Thursday released Safari Technology Preview 144, 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 144 includes bug fixes and performance improvements for Web Inspector, CSS, Web Animations, JavaScript, WebAuthn, Web API, Accessibility, Media, Security Policy, and Web Extensions.

‌Safari Technology Preview‌ release 144 is built on the new Safari 15.4 update included in macOS Monterey, and as such, it includes several Safari 15 features.

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

Release 144

Note: Tab Groups do not sync in this release.

Web Inspector

  • Fixed page reloading and showing an empty inspector on pages with container queries (r291824)
  • Elements Tab
    • Fixed $0 not being displayed for the selected node after switching to another tab (r291729)
    • Fixed unwanted extra dash when autocompleting CSS variable names in the Styles panel (r291740)
    • Fixed inline swatch popovers not being hidden when the inline swatch is removed (r291628)
  • Console Tab
    • Fixed console.screenshot to no longer have extra transparent pixels at the bottom of viewport screenshots (r291519)


  • Added Typed OM support for container units (r291524)
  • Fixed CSS cascade regarding logical properties (r291546)
  • Fixed incorrect handling of NaN inside calc() for top-level calculation (r291911)
  • Let revert-layer roll back to presentational hints (r291594)
  • Implemented border-image serialization (r291537)
  • Preserved repeat() notation when serializing grid-templates (r291956)
  • Reduce memory usage for large, sparse grids (r291952)
  • Handled finite value with infinite step in round() for calc() (r291841)
  • Fixed incorrect resolution of percentage grid-gaps within subgrids (r291953)

Web Animations

  • Enabled support for mutable timelines by default (r291868)


  • Changed Date.parse to stop returning numbers with fractional part (r291603)
  • Fixed class field initializer with extra parentheses (r291577)


  • Added getAssertion support for virtual HID authenticators (r291624)
  • Specified correct ASCPublicKeyCredentialKind in configureAssertionOptions (r291761)
  • Updated to pass along timeout to ASA and ignore timeout for conditional mediation requests (r291625)


  • Added support for focused and visible ServiceWorkerWindowClient states (r291888)
  • Added a check for whether the origin can access storage in the Storage API (r291726)
  • Disabled custom storage paths for IndexedDB and LocalStorage by default (r291909)
  • Fixed PointerEvent.movementX to not always be 0 (r291886)
  • Fixed Context2D drawImage(img, x, y, w, h) to not throw IndexSizeError when width or height are 0 (r291748)
  • Fixed fetching a Blob URL with an unbounded Range header to correctly generate a Content-Range response header (r291622)
  • Implemented CSSNumericValue.mulCSSNumericValue.divCSSNumericValue.addCSSNumericValue.subCSSNumericValue.max, and CSSNumericValue.min (r291597)
  • Implemented ServiceWorkerWindowClient.focus (r291938)


  • Included initial accessibility support for display: contents (r291570)


  • Fixed a bug where clicking anywhere on the progress bar pauses some MSE video implementations (r291629)
  • Fixed video playback for HEVC-encoded video with a lot of b-frames and a wide sliding window (r291813)

Security Policy

  • Fixed website policies not being respected when doing COOP-based process swap (r291606)

Web Extensions

  • Fixed a crash clicking on Safari App Extension toolbar items

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.