TypeScript Mapped Types

Mapped types allow you to create new types by iterating over the keys of an existing type.

Basic Syntax

type OptionsFlags<Type> = {
  [Property in keyof Type]: boolean;
};

Mapping Modifiers

Use readonly and ? to affect mutability and optionality. Prefix with + (default) or - to add or remove them.

type CreateMutable<Type> = {
  -readonly [Property in keyof Type]: Type[Property];
};

Key Remapping via as

Map keys to new property names using the as clause, often combined with Template Literal Types.

type Getters<Type> = {
  [Property in keyof Type as `get${Capitalize<string & Property>}`]: () => Type[Property]
};

• Filtering: Map a key to never to remove it from the resulting type.

References

• Source: 00_Raw/typescript-handbook.md
• typescript-moc
• typescript-type-operators
• typescript-template-literals
• typescript-objects