type-fest/source/basic.d.ts

/**
Matches a [`class`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes).

@category Class
*/
export type Class<T, Arguments extends unknown[] = any[]> = {
	prototype: Pick<T, keyof T>;
	new(...arguments_: Arguments): T;
};

/**
Matches a [`class` constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes).

@category Class
*/
export type Constructor<T, Arguments extends unknown[] = any[]> = new(...arguments_: Arguments) => T;

/**
Matches an [`abstract class`](https://www.typescriptlang.org/docs/handbook/classes.html#abstract-classes).

@category Class

@privateRemarks
We cannot use a `type` here because TypeScript throws: 'abstract' modifier cannot appear on a type member. (1070)
*/
// eslint-disable-next-line @typescript-eslint/consistent-type-definitions
export interface AbstractClass<T, Arguments extends unknown[] = any[]> extends AbstractConstructor<T, Arguments> {
	prototype: Pick<T, keyof T>;
}

/**
Matches an [`abstract class`](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-2.html#abstract-construct-signatures) constructor.

@category Class
*/
export type AbstractConstructor<T, Arguments extends unknown[] = any[]> = abstract new(...arguments_: Arguments) => T;

/**
Matches a JSON object.

This type can be useful to enforce some input to be JSON-compatible or as a super-type to be extended from. Don't use this as a direct return type as the user would have to double-cast it: `jsonObject as unknown as CustomResponse`. Instead, you could extend your CustomResponse type from it to ensure your type only uses JSON-compatible types: `interface CustomResponse extends JsonObject { … }`.

@category JSON
*/
export type JsonObject = {[Key in string]: JsonValue} & {[Key in string]?: JsonValue | undefined};

/**
Matches a JSON array.

@category JSON
*/
export type JsonArray = JsonValue[] | readonly JsonValue[];

/**
Matches any valid JSON primitive value.

@category JSON
*/
export type JsonPrimitive = string | number | boolean | null;

/**
Matches any valid JSON value.

@see `Jsonify` if you need to transform a type to one that is assignable to `JsonValue`.

@category JSON
*/
export type JsonValue = JsonPrimitive | JsonObject | JsonArray;