Base

Maybe

Returns a union of the type and a potentially missing value, such as undefined or null.

type Maybe<T> = NoInfer<T | undefined | null>;

Note: NoInfer is used to provide a more readable hover overlay.

Primitive

Represents a primitive data type in JavaScript. A primitive is not an object and has no methods or properties.

type Primitive = string | number | boolean | bigint | symbol | null | undefined;

AnyFn

Represents a function that can take any number and type of arguments and return any. Sometimes TypeScript forces you to use it in generics.

type AnyFn = (...args: any[]) => any;

ExpandRecord

Forces TypeScript to expand an object type into its full structure. Useful where TypeScript displays a complex type as a combination of aliases instead of a fully resolved object shape.

type ExpandRecord<T> = { [K in keyof T]: T[K] } & {};

Note: Only affects how the type is displayed in editor hovers/error messages; it does not change the underlying type.

Forces TypeScript to distribute and fully materialize a union type. Improves editor hover/error messages readability when unions are derived from complex conditional types or other inferred constructs.

type ExpandUnion<T> = T extends infer U ? U : never;