The beta was published on June 26. The production version is slated for release in August, according to the roadmap for the platform.
As proposed, TypeScript 4.0 boosts speed in the
build mode, with the caching of semantic diagnostics in the builder written to the disk with
.tsbuildinfo, to benefit the next incremental build. This is intended to fix a situation in which compiling a program after a previous compile with errors under
--incremental would be very slow when using the