TypeScript: Union types

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Union types let us tell TypeScript a value can be of one type, or another type.

Example:

const run = (a: number | string) => {
  //...
}

In this case the parameter a can be either a string, or a number, but nothing else.

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