TypeScript 3.9 Released

TypeScript 3.9 features speed improvements in compiler and editing experience as well as freedom from friction and papercuts.

Microsoft announced the release of TypeScript 3.9. The latest release comes with focus on performance, polish, and stability.
 
Microsoft said that it has worked on speeding up the compiler and editing experience and getting rid of friction and papercuts as well as reducing bugs and crashes.
 
3.9 features Improvements in Inference and Promise.all, Speed Improvements, // @ts-expect-error Comments, Uncalled Function Checks in Conditional Expressions and Editor Improvements.
 
 
Source: TypeScriptlang.org
 
Editor improvements in the release include CommonJS Auto-Imports in JavaScript, Quick Fixes for Missing Return Expressions, Code Actions Preserve Newlines, and Support for “Solution Style” tsconfig.json Files.
 
Version 3.9 also features a new type operator called awaited, which enables you to accurately model the way that Promise unwrapping works in JavaScript.
 
Regarding speed improvements, the company said that 3.9 brings around a 25% reduction in the material-ui-styles project’s compile time.