Mapped Types

A mapped type is derived from an existing type by modifying the properties’ names or accessibility (e.g. readonly) in the new type.

Example:

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// Existing Type
type User = {
  age: number;
  firstName: string;
  lastName: string;
}

// Mapped Type
type PartialUser = {
  [P in keyof User]?: User[P];
};

More about mapped types ➝