According to Microsoft, TypeScript 5.0 is not a particularly disruptive release, which means the upgrade process should be relatively simple.
This release includes a number of new features and improvements that make the language smaller, simpler, and faster.
Among the updates is that the new decorators standard has been implemented. Decorators enable developers to customize classes and their members so that they can be easily reused. TypeScript had for a long time supported an experimental version of decorators which are now considered legacy technology, though Microsoft intends to continue supporting them for a while still. They required you to use an opt-in compiler flag in order to make use of them, whereas the new decorators can be used without.
Also new in TypeScript 5.0 is that developers can add a “const” modifier to a type parameter declaration. The “const” modifier makes a variable constant, whereas by default TypeScript will infer and choose a type that is meant to be general.
Developers will now be able to more easily support multiple configuration files using the “extends” field, which copies fields from “compilerOptions.” TypeScript 5.0 enables “extends” to take multiple fields.
There are also new features that better support EcmaScript module (ESM) projects in Node and in bundlers, such as the “–ModuleResolution bundler.”
Other new features in this release include union enums, resolution customization flags, and support for the export type *.