Using Third Party Types

What you'll learn

  • use types from libraries or install them from DefinitelyTyped
  • write types for libraries whose types are not available in DefinitelyTyped
  • extends types for libraries

Using Types from TypeScript and Libraries

Many open source projects include type definition by default, e.g. redux, redux-thunk. When you use those package with TypeScript, the package would just work without additional configuration on your side.

However, some popular packages does not comes with type definition, e.g. react, react-dom, and classnames. However, as many people use them with TypeScript, you can install the type definition separately (which are maintained separately). For instance, we install @types/classnames for classnames package.

Do It: Installing Type Definition

Convert <Slide /> component (slide.tsx) and install the required type definition.

Create Types for Third-Party Libraries

Example: simple-format-number

declare module 'simple-format-number' {
export default function format(
num: number,
options?: {
fractionDigits?: number;
symbols?: {
decimal?: string;
grouping?: string;
): string;

Extending Third-Party Typing

Sometimes, the type definition of the libraries (and even those comes with TypeScript) may be outdated and you may want to extends them. This section teach you how to do that.

Examples: share function that use navigator.share Web API.

Examples: Image component that use loading props on img tag.

Examples: DateInput using JQuery

Issue on this page? Report here