Announcing TypeScript 3.5

Built on top of all this is also a language service which uses all the type information TypeScript has to provide powerful editor functionality like code completions, find-all-references, quick fixes, and refactorings. This regression was serious not just because it led to much higher build times for TypeScript code, but because editor operations for both TypeScript and JavaScript users became unbearably slow. Thanks to Wenlu Wang (GitHub user @Kingwl), TypeScript supports a useful new refactoring to extract types to local type aliases.

Source: devblogs.microsoft.com