Release Notes for Safari Technology Preview 14

Safari Technology Preview Release 14 is now available for download for both macOS Sierra and OS X El Capitan 10.11.6. If you already have Safari Technology Preview installed, you can update from the Mac App Store’s Updates tab. This release covers WebKit revisions 205519–206196.

This release of Safari Technology Preview will be one of the last that will install and run on OS X El Capitan. To continue testing or living on the latest enhancements to Safari and WebKit, please upgrade to macOS Sierra in the next few weeks.

Safari Extensions

  • Fixed an issue where content blocker extensions delivered with apps wouldn’t be applied in Safari Technology Preview

Custom Elements

  • Enabled Custom Elements API (r205527)

Fetch API

  • Changed combining Access-Control-Request-Headers with ',' instead of ', ' (r206014)
  • Updated Referrer and Origin headers handling to prevent unnecessary CORS preflight (r206009)


  • Changed ES6 classes to allow the creation of a static method with name “arguments” (r205856)
  • Improved performance for Map and Set (r205520)
  • Improved performance of Function.prototype.bind (r205848)
  • Fixed language tag parsing in Intl constructors (r205568)

Web APIs

  • Implemented URLSearchParams (r205893, r206168)
  • Added support for HTMLIFrameElement.allowFullscreen, input.minLength, and textArea.minLength attributes (r205686, r205524)
  • Added support for HTMLSourceElement.prototype.sizes and HTMLSourceElement.prototype.srcset (r206140)
  • Fixed an issue to allow setting input.type to file after being set to another type (r205912)
  • Fixed attribute reflection as a URL for frame.longDesc, iframe.longDesc and HTMLObjectElement.codebase (r205685, r205690)
  • Fixed ol.start to return the correct value for reversed lists when it is not explicitly set (r205689, r205806)
  • Changed hspace, vspace, width, height attributes of HTMLImageElement along with the hspace and vspace attributes of HTMLObjectElement to be unsigned (r205665, r205655, r205691)
  • Changed pageXOffset and pageYOffset attributes of Window to be replaceable (r206109)
  • Changed the window.performance object wrapper to stay alive as long as the associated frame (r205823)
  • Changed the invalid default value of HTMLTrackElement.kind to the metadata state (r205791)
  • Fixed handling a negative radius in the coords attribute of an HTMLAreaElement in a circle shape (r205565)
  • Moved to (r205839)
  • Updated HTMLAppletElement and HTMLAreaElement shape parsing to align with specifications (r206131, r205562)
  • Exposed the WebCrypto algorithms via KeyAlgorithm dictionary (r205941)
  • Dropped legacy canvas.probablySupportsContext() (r205554)
  • Dropped support for <isindex> (r205858)

Apple Pay

  • Added a new -webkit-appearance CSS property for Apple Pay buttons (r205980)
  • Fixed presenting a payment sheet when a sheet is already active in another window (r206176)

Web Inspector

  • Added a button to the navigation bar to toggle the Control Flow Profiler (r205674)
  • Added support for drag-and-drop of CSS classes and ids onto DOM nodes (r206008)
  • Added JavaScript completion for ES6 keywords and global variables (r206015)
  • Added a popover to show Resource Timing details in Network waterfall displays (r205578)
  • Added a warning message in the Debugger sidebar when breakpoints are disabled (r205651)
  • Changed the Debugger Scope sidebar to show “Local” instead of “Closure” when paused in an anonymous function (r206105)
  • Fixed selecting the call frame in the Debugger sidebar on initial pause and added an indicator next to active call frame (r205946)
  • Fixed debugger popover title and code horizontal alignment (r205832)
  • Fixed Command-Z (⌘Z) behavior when editing CSS selectors in the Styles sidebar (r205754)
  • Improved Element Search (⇧⌘C) to bring the inspector page’s window forward and highlight elements without requiring mouse movement (r206091, r206093)
  • Fixed Properties section layout when clicking the “Show All” checkbox of the Computed Styles section (r205555)
  • Fixed a bug causing the color picker to stop working in the Styles sidebar after the first color change (r206092)
  • Fixed a bug where reloading unexpectedly switches to the Storage tab (r206195)
  • Implemented Copy CSS Selector and Copy Xpath Selector context menus (r206059)
  • Improved element search to bring the inspected page’s window forward (r206091)
  • Made console session dividers more pronounced (r206057)


  • Added support for new emoji group candidates (r205657)


Starting in Release 14, Safari Technology Preview now includes regular updates and bug fixes to Safari’s WebDriver implementation. You can run your WebDriver tests with the updated driver by using the safaridriver executable that is included in the Safari Technology Preview application bundle. By default, this is located at: /Applications/Safari Technology The driver executable located at /usr/bin/safaridriver will continue to launch Safari 10 on macOS Sierra and OS X El Capitan.

For more information about using WebDriver with Safari, check out the blog post WebDriver Support in Safari 10.