Release Notes for Safari Technology Preview 18

Safari Technology Preview Release 18 is now available for download for macOS 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 208261–208427.

Input Events

  • Turned on the Input Events experimental feature by default (r208266)


  • Fixed an issue where exception descriptions didn’t know how to handle Symbol values (r208410)

Shadow DOM

  • Added support for loading stylesheets for link elements that are inside Shadow DOM trees (r208302, r208403)

Web Inspector

  • Added support for pausing, stepping and debugging Web Workers in the Debugger tab (r208304)
  • Fixed creating a new pseudo-selector in the Styles sidebar when it doesn’t work on the first attempt (r208270)
  • Fixed a stack overflow when searching a timeline recording for JavaScript function names (r208348)


  • Changed how minmax(auto, <flex>) should be serialized per the CSS Grid spec (r208277)
  • Fixed CSS.supports("font-variation-settings", "'wght' 500") so it does not erroneously return false (r208321)
  • Fixed filter functions grayscale(), invert(), opacity(), and sepia() so they clamp values over 100% (r208294)
  • Fixed the slotted() pseudo selector so that it works with id selectors (r208390)


  • Fixed a bug where Safari does not emit compositionend if blurred for dead key or Japanese IME (r208406)

Indexed Database 2.0

  • Changed IDBIndex to handle rename behavior properly when version change transaction aborts (r208380)
  • Changed IDBObjectStore to handle rename behavior properly when version change transaction aborts (r208389)
  • Renamed IDBKeyRange.contains() to IDBKeyRange.includes() (r208359)
  • Added support for binary keys (r208349)
  • Added support for IDBIndex.getAll() and IDBIndex.getAllKeys() (r208261)
  • Corrected which exceptions are thrown during IDBObjectStore and IDBIndex renaming (r208383)


  • Fixed a crash that would happen when attempting to clear selection on ARIA listboxes (r208384)


  • Made printing to PDF produce internal links when the HTML has internal links (r208347)

HTTP Authentication

  • Changed Safari’s HTTP authentication UI to not block switching tabs, navigating to other websites, or closing tabs

Web APIs

  • Changed resizeTo, resizeBy, moveTo, or moveBy to do nothing in windows that weren’t created by
  • Implemented new user interface for HTML interactive form validation behind an experimental flag