# Safari Technology Preview 17 Release Notes Preview the latest web technology updates including: Safari Extensions, Custom Elements, Web APIs, Input Events, URL Parser, Fetch API, JavaScript, Web Inspector, CSS, Media, Networking, Indexed Database 2.0, and bug fixes. ## Overview [Safari Technology Preview Release 17](https://webkit.org/blog/6017/introducing-safari-technology-preview/) is now [available for download](https://webkit.org/downloads/) 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 [207669–208261](https://trac.webkit.org/log/?stop_rev=207669&rev=208261&limit=999). ### Safari Extensions - Removed NPAPI Plug-in support from `.safariextz` Safari Extensions ### Custom Elements - Enabled Custom Elements everywhere by default ([r208201](https://trac.webkit.org/changeset/208201)) - Changed Custom Elements reactions to have a queue per element ([r207810](https://trac.webkit.org/changeset/207810)) - Enqueued `attributeChanged` and `connected` callbacks when upgrading a custom element ([r207710](https://trac.webkit.org/changeset/207710)) - Custom Elements reactions are now enqueued for HTML API ([r208082](https://trac.webkit.org/changeset/208082)) and CSS OM APIs ([r208176](https://trac.webkit.org/changeset/208176)) ### Web APIs - Implemented `rel=noopener` ([r207840](https://trac.webkit.org/changeset/207840)) - Enabled stylesheets loading via a `link` element inside Shadow DOM subtrees ([r208403](https://trac.webkit.org/changeset/208403)) - Added support for HTML formatted content from `event.dataTransfer.getData('text/html')` and `event.clipboardData.getData('text/html')` in `onpaste` or `ondrop` events ([r207797](https://trac.webkit.org/changeset/207797)) ### Input Events - Added support to fire `insertReplacementText` input events when holding down a key to choose an accented character ([r208143](https://trac.webkit.org/changeset/208143)) - Implemented `InputEvent.getTargetRanges()` ([r207670](https://trac.webkit.org/changeset/207670)) - Implemented support for `insertFromDrop` and `deleteByDrag` ([r208014](https://trac.webkit.org/changeset/208014)) - Implemented support for `insertFromComposition`, `deleteByComposition`, `insertCompositionText`, and `deleteCompositionText` input types for Input Events ([r207698](https://trac.webkit.org/changeset/207698)) - Implemented support for `InputEvent.dataTransfer` ([r207841](https://trac.webkit.org/changeset/207841)) ### URL Parser - Matched the behavior of the old URL parser when `%2E` is in the URL path ([r207805](https://trac.webkit.org/changeset/207805)) - Prevented interpreting host of URLs with unrecognized schemes as an IPv4 address ([r208086](https://trac.webkit.org/changeset/208086)) ### Fetch API - Ensured the redirection count is no more than 20 in case of cross origin requests ([r208046](https://trac.webkit.org/changeset/208046)) - Ensured redirections are upgraded only if declared by CSP policy ([r207752](https://trac.webkit.org/changeset/207752)) - Changed ReadableStream to only clone the second branch ([r208039](https://trac.webkit.org/changeset/208039)) ### JavaScript - Fixed arrow functions with concise bodies to be able to return regular expressions ([r207798](https://trac.webkit.org/changeset/207798)) - Fixed `String.prototype.replace()` to throw an `OutOfMemoryError` when using too much memory ([r207861](https://trac.webkit.org/changeset/207861)) - Enabled `JSON.stringify` to handle an ES6 Proxy that has an array element context ([r208123](https://trac.webkit.org/changeset/208123)) ### Web Inspector - Added support for Custom Elements in Web Inspector ([r208218](https://trac.webkit.org/changeset/208218)) - Enabled showing Shadow DOM scoped styles in Web Inspector ([r208199](https://trac.webkit.org/changeset/208199)) - Added a pinned tab for settings with various text editor preferences ([r208091](https://trac.webkit.org/changeset/208091)) - Breakpoints not working in scripts with unicode characters ([r208097](https://trac.webkit.org/changeset/208097)) - Fixed the alignment for arrows in the Styles scope bar item ([r208190](https://trac.webkit.org/changeset/208190)) - Fixed the ⌘+ shortcut not increasing the size of Web Inspector’s user interface ([r207850](https://trac.webkit.org/changeset/207850)) - Fixed Open Resource Dialog to jump to the last line when entering `:*n*` where “*n*” is greater than the number of lines in the file ([r208188](https://trac.webkit.org/changeset/208188)) - Improved the debugger highlight in some exception cases ([r208260](https://trac.webkit.org/changeset/208260)) - Improved Quick Open sorting algorithm ([r207782](https://trac.webkit.org/changeset/207782)) - Improved `console.log` support in Web Workers ([r208010](https://trac.webkit.org/changeset/208010)) - Included parameter strings for native `CustomElementRegistry` methods in the console ([r208072](https://trac.webkit.org/changeset/208072)) - Prevented showing empty Closure sections in the Scope chain ([r207784](https://trac.webkit.org/changeset/207784)) ### CSS - Avoided unnecessary full style resolution in `getComputedStyle` for non-inherited properties ([r207755](https://trac.webkit.org/changeset/207755)) - Fixed `backdrop-filter` to render properly when removed and then re-added ([r207722](https://trac.webkit.org/changeset/207722)) - Fixed rendering dynamically-added `backdrop-filter` to a clip-path’d element with 3D transform ([r207723](https://trac.webkit.org/changeset/207723)) - Changed behavior to create a stacking context while an animation is running when the animation keyframes affect stacking context properties ([r208025](https://trac.webkit.org/changeset/208025)) - Prevented painting text selection within an SVG mask ([r207692](https://trac.webkit.org/changeset/207692)) - Corrected the blur radius for `filter: drop-shadow()` ([r208058](https://trac.webkit.org/changeset/208058)) - Changed style resolver to be updated lazily ([r207669](https://trac.webkit.org/changeset/207669)) ### Media - Allowed multiple playing videos on a page with `autoplay` and `playsinline` attributes ([r208149](https://trac.webkit.org/changeset/208149)) - Fixed WebAudio to resume when moving from background to foreground tab ([r208092](https://trac.webkit.org/changeset/208092)) - Fixed video playback stalls when seeking beyond the buffered range for some video sites ([r207694](https://trac.webkit.org/changeset/207694)) - Added support for wide gamut in Quick Look image popovers ([r208020](https://trac.webkit.org/changeset/208020)) ### Networking - Changed the preloading behavior to match the behavior on iOS, where resources like images are loaded at a lower priority ([r208049](https://trac.webkit.org/changeset/208049)) ### Indexed Database 2.0 - Support renaming IDBObjectStores ([r207641](https://trac.webkit.org/changeset/207641)) and IDBIndexes ([r207761](https://trac.webkit.org/changeset/207761)) - Implemented `IDBTransaction.objectStoreNames()` ([r207821](https://trac.webkit.org/changeset/207821)) - Implemented `IDBObjectStore.openKeyCursor()` ([r207845](https://trac.webkit.org/changeset/207845)) - Implemented `IDBObjectStore.getAll()` and `IDBObjectStore.getAllKeys()` ([r208194](https://trac.webkit.org/changeset/208194)) - Implemented `IDBIndex.getAll()` and `IDBIndex.getAllKeys()` ([r208261](https://trac.webkit.org/changeset/208261)) ### Bug Fixes - Fixed an issue where JavaScript dialogs (`alert`, `confirm`, `prompt`) and Safari’s external navigation confirmation prompt showed empty messages --- Copyright © 2026 Apple Inc. 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