Yesterday Microsoft dev team announced the release candidate version of TypeScript 3.9 RC. This version focuses mostly on improvements in performance and stability improvements like:
The new version provides some serious performances improvements. After detecting poor compilation speed with material-ui packages, the series of fixed were made to improve cases involving large unions, intersections, conditional & mapped types. It is said that version 3.9 achieved a ~40% reduction in material-ui’s compile-time.
Recent versions of TypeScript have had some changes to the way
Promise.race functions are declared which generated few regressions linked to mixing
undefined values. In 3.9 that was fixed along with some improvements to the inference process.
awaitedType is gone (as for now)
A new type of operator called
awaited with a goal to accurately design the unwrapping of
awaited is still in progress and requires some more work before they can roll it out to everyone with confidence.
Quite a lot right? And these are only some of the changes! If you would like to read more about the new version the Microsoft dev blog contains the whole list of features and improvements available inTypScript 3.9 RC.