This is the one TypeScript users have been transpiling for years. WebKit's latest preview implements the TC39 Explicit Resource Management proposal — ratified to Stage 4 last year — which means `using` and `await using` now resolve natively in V8, SpiderMonkey, and WebKit alike. The last cross-browser gap for deterministic cleanup is gone; if you've been shipping the polyfill to paper over Safari, you can start planning its removal. The keyword isn't the only thing in the drop. The same preview carries two WebAssembly additions — multi-memory and relaxed SIMD — plus streaming upload bodies in `fetch()`, SVG clipboard support, and five new CSS text properties. One caveat worth keeping in front of you: this is a Technology Preview, not stable Safari. Treat native `using` as a signal the runway is clear, not as something to hand real users tomorrow.