type-fest/source/basic.d.ts

/// <reference lib="esnext"/>

// TODO: This can just be `export type Primitive = not object` when the `not` keyword is out.
/**
Matches any [primitive value](https://developer.mozilla.org/en-US/docs/Glossary/Primitive).
*/
export type Primitive =
	| null
	| undefined
	| string
	| number
	| boolean
	| symbol
	| bigint;

// TODO: Remove the `= unknown` sometime  in the future when most users are on TS 3.5 as it's now the default
/**
Matches a [`class` constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes).
*/
export type Class<T = unknown, Arguments extends any[] = any[]> = new(...arguments_: Arguments) => T;

/**
Matches any [typed array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray), like `Uint8Array` or `Float64Array`.
*/
export type TypedArray =
	| Int8Array
	| Uint8Array
	| Uint8ClampedArray
	| Int16Array
	| Uint16Array
	| Int32Array
	| Uint32Array
	| Float32Array
	| Float64Array
	| BigInt64Array
	| BigUint64Array;

/**
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 { … }`.
*/
export type JsonObject = {[key: string]: JsonValue};

/**
Matches a JSON array.
*/
export interface JsonArray extends Array<JsonValue> {}

/**
Matches any valid JSON value.
*/
export type JsonValue = string | number | boolean | null | JsonObject | JsonArray;

declare global {
	interface SymbolConstructor {
		readonly observable: symbol;
	}
}

/**
Matches a value that is like an [Observable](https://github.com/tc39/proposal-observable).
*/
export interface ObservableLike {
	subscribe(observer: (value: unknown) => void): void;
	[Symbol.observable](): ObservableLike;
}