--- title: Safari Technology Preview 4 Release Notes framework: safari-technology-preview-release-notes role: article role_heading: Article path: safari-technology-preview-release-notes/stp-release-4 --- # Safari Technology Preview 4 Release Notes Preview the latest web technology updates including: Networking, Media, JavaScript, CSS, Web APIs, Web Inspector, Rendering, Accessibility, and bug fixes. ## Overview Overview Safari Technology Preview Release 4 is now available for download. If you already have Safari Technology Preview installed, you can update from the Mac App Store’s Updates tab. Release 4 of Safari Technology Preview covers WebKit revisions 199865–200417. Networking Allow non-standard HTTP headers in WebSocket handshakes, which makes the 1Password extension work again (r200120, r200219) Media Fixed Netflix video playback (r200172) JavaScript Disabled Symbol.isConcatSpreadable due to performance concerns; is expected to return in the next release (r200149) Made super() available to object literals, not just ES6 classes (r199927) Sped up calling bound functions with no bound arguments by 4x (r199946) Implemented String.prototype.localeCompare from ECMA-402 (r199967) Optimized JSON.parse for a 1–2.5% improvement in Kraken json-parse-financial (r199968) Implemented RegExp.prototype.@@replace and use it for String.prototype.replace (r200117) Implemented spec changes for String.prototype.padStart and String.prototype.padEnd (r200194, r200210) Unified how Math.pow() is optimized across all JIT tiers (r200208) Made Reflect.toString() be [object Object] not [object Reflect] (r200355) CSS Made -webkit-image-set work inside CSS variables (r199884) Changed transitions to no longer animate to/from auto values (r200360) Implemented proper handling of animation-delay with a negative delay (r200042) Started parsing play-state as part of the animation shorthand (r200043) Made toggling animation-play-state not restart a finished animation (r200047) Fixed a regression which caused position: absolute pseudo elements to inherit text-decoration (r200302) Moved CSS Grid behind a runtime switch that is currently enabled by default (r200215, r200389) Started implementation of auto-fill and auto-fit for CSS Grid (r200182, r200368) Fixed computed style of grid-template-columns and grid-template-rows properties (r199981) Fixed a bug with positioned grid items in vertical writing mode (r199874) Fixed alignment with CSS Grid content distribution (r200181) Improved user agent styles for elements (r199869) Web APIs Fixed wheel events so they fire with body, html { height: 100% } (r200247) Marked IndexedDB constructors as hidden on the worker global object until it is supported (r199889) Made ping attribute for anchor elements only work for http/https URLs (r199900) Renamed Shadow DOM’s getAssignedNodes to assignedNodes and support flattened option (r200285) Removed Shadow DOM’s Node.prototype.rootNode because it was not compatible with existing websites (r200297) Made document.currentScript return null when executing a script inside a shadow tree (r200327) Fixed clicks sometimes being ignored inside button elements when the mouse moves (r200414) Web Inspector Made console a namespace object (like Math and JSON), allowing functions to be called unbound (r200350, r200373) Fixed an issue where scripts would not load due to Esprima.js not being found (r200229) Started showing dynamically added