TypeScript 4.1
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-1.html
Template Literal Types
Key Remapping in Mapped Types
Recursive Conditional Types
noUncheckedIndexedAccess
paths without baseUrl
checkJs Implies allowJs
React 17 JSX Factories
TypeScript 4.1 supports React 17’s upcoming jsx and jsxs factory functions through two new options for the jsx compiler option:
react-jsx
react-jsxdev
compilerOptions.jsxのこと
Editor Support for the JSDoc @see Tag
Breaking Changes
lib.d.ts
abstract Members Can't Be Markd async
any/unknown Are Propagated in Falsy Positions
resolve’s Parameters Are No Longer Optional in Promises
Conditional Spreads Create Optional Properties
Unmatched parameters are no longer related