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WebKitJon Davis10 min readrelease notesintermediate

Release Notes for Safari Technology Preview 252

Read on webkit.org

Summary

Safari Technology Preview 252 adds several WebKit platform updates, including new CSS features like named-feature() in @supports and unprefixed user-select, plus bug fixes across accessibility, animations, HTML, and JavaScript. The release also corrects worker termination, Promise.try behavior, and line‑clamp rendering, which can affect Safari‑targeted web apps.

  • `named-feature()` is now supported in @supports conditions, enabling feature‑querying of custom CSS features.
  • `Promise.try()` now resolves with PromiseResolve, removing an unnecessary extra promise layer.
  • `worker.terminate()` correctly stops workers blocked in Atomics.wait or WebAssembly atomic.wait, fixing potential hangs.
  • `line-clamp` and `text-overflow: ellipsis` bugs are fixed, restoring expected truncation behavior in mixed inline/block contexts.

Web developers building for Safari need to know the new CSS capabilities and critical bug fixes to avoid regressions and leverage the updated platform.

6/10
javascripthtmlcssaccessibilityanimations

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