Union Type

Union type is a type that allows a value to be one of several possible types.

For example, in Typescript:

type Id = string | number

This means an Id can be either a string or a number.

Union types are useful for:

• Modeling values with several valid shapes
• Representing state
• Handling values from dynamic systems
• Making invalid cases harder to express

Union types are often combined with literal types to model a fixed set of allowed values.

Anki

id: union-type-definition deck: Computer Science::Data Types tags: data-types union-type

Q: What is a union type? A: A union type allows a value to be one of several possible types.

id: union-type-typescript-example deck: Computer Science::Data Types tags: data-types union-type typescript

Q: What does type Id = string | number mean in TypeScript? A: It means an Id can be either a string or a number.