Microsoft Announces TypeScript 3.0 (neowin.net)

Microsoft released version 3.0 of TypeScript, which Microsoft describes as an "extension" of JavaScript "that aims to bring static types to modern JavaScript." Quoting Microsoft's Developer Tools blog: The TypeScript compiler reads in TypeScript code, which has things like type declarations and type annotations, and emits clean readable JavaScript with those constructs transformed and removed. That code runs in any ECMAScript runtime like your favorite browsers and Node.js. At its core, this experience means analyzing your code to catch things like bugs and typos before your users run into them; but it brings more than that. Thanks to all that information and analysis TypeScript can provide a better authoring experience, providing code completion and navigation features like Find all References, Go to Definition, and Rename in your favorite editor.
Neowin reports: With any major version release, it is not unexpected for breaking changes to be introduced and that's certainly the case for TypeScript 3.0. One obvious change is that with "unknown" becoming a new type, it is now a reserved type name and can no longer be used in type declarations. Otherwise, there's a range of API breaking changes due to a number of functions and internal methods being deprecated or being made internal.
On the plus side, TypeScript 3.0 reportedly has improved error messages, along with project references that let TypeScript projects have dependencies on other TypeScript projects.