TypeScript 3.8

TypeScript 3.8 (static type-checking for JS)

Features: new & upcoming ECMAScript standards

Type-Only Imports and Exports

import type { SomeThing } from "./some-module.js";

ECMAScript Private Fields export * as ns Syntax Top-Level await JSDoc Property Modifiers Better Directory Watching on Linux and watchOptions “Fast and Loose” Incremental Checking

Breaking Changes

• Stricter Assignability Checks to Unions with Index Signatures const obj1: { [x: string]: number } | { a: number };
• Optional Arguments with no Inferences are Correctly Marked as Implicitly

  function foo(f: () => void) {
      // ...
  }

  foo((param?) => {
      // ...
  });