TypeScript extend type declaration of a module/package

typescript_fix_package_types.md

TypeScript: Extend package types

// When a package doesn't have any types, we can silence TS with
import * as someLibrary from "some-library"

// And extend some types if we want better type safety
declare module "some-library" {
  export function missingFunctionDeclaration(): {
    x: number
    y: number
    someOtherValue: string
  }
}

// To extend a package's types, look at the package's
// source code and declare types accordingly

// That's it