Union Type

Definitions

1. A type that represents a value which can be one of several specified types. Written as A | B in TypeScript, the compiler ensures you handle all possible variants before accessing type-specific properties.

   In plain English: A type that says 'this value could be one of several types' — and the compiler makes sure you check which one it is before using it.

   Example: "The API returns string | number, so you need a type guard before calling .toFixed()."

Related Terms

• Declaration File
• Discriminated Union
• Generics
• Null Safety
• Nullable
• Option Type
• Static Typing
• Strong Typing
• Type Guard
• Utility Types
• Phantom Type
• Structural Typing
• Partial Type
• Type Predicate
• Utility Type
• Zod