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The release candidate for TypeScript 5.5, a high-level programming language, is now available from Microsoft. TypeScript adds static typing and optional type annotations to JavaScript. It is free and open-source. With its ability to transpile to JavaScript, it is well-suited for building massive apps.

Announcing TypeScript 5.5 RC

Today we are excited to announce the availability of the release candidate of TypeScript 5.5. To get started using the RC, you can get it through NuGet, or through npm with the following command: npm install -D typescript@rc

What’s New Since the Beta?

Since the beta, we’ve made a few changes that we wanted to call out.

For one, we  added support for ECMAScript’s new Set methods. Additionally, we’ve adjusted the behavior of  TypeScript’s new regular expression checking to be slightly more lenient, while still erroring on questionable escapes that are only allowed per ECMAScript’s Annex B.

We’ve also added and documented even more  performance optimizations: notably, skipped checking in transpileModule and optimizations in how TypeScript filters contextual types. These optimizations can lead to faster build and iteration time in many common scenarios.

Announcing TypeScript 5.5 RC - TypeScript