To type arrays, we use generics.

Suppose you want an array to only contain numbers.

This is how you type it:

const nums: Array<number> = [1, 2, 3]

You can now add numbers to the array, but if you add a string for example you’ll have an error:

We use generics often with useState in React:

type GitHubData = {
  avatar_url: string
  name: string
  created_at: string
  bio: string
}

function App() {
  const [data, setData] = useState<GitHubData>()
}

Lessons in this unit:

0:	Introduction
1:	Your first TypeScript program
2:	Types
3:	Typing functions
4:	The editor helps you with type errors
5:	Running TypeScript code
6:	Valid types
7:	Type aliases and interfaces
8:	Union types
9:	▶︎ Typing arrays with generics
10:	The DX of editing TypeScript
11:	There's more...
12:	TypeScript declare a type that can be a string or array of strings
13:	TypeScript, disable checks for `declared but its value is never read`
14:	Object destructuring with types in TypeScript
15:	TypeScript Tutorial
16:	Zod: Type-Safe Schema Validation for TypeScript
17:	How I fixed some trouble importing types in .d.ts files