aliases.md

typelab / aliases

Handy TypeScript type aliases for everyday things like arrays, objects, functions, and promises. It also includes special cases like primitive, nullable, nullish, and undefinable types.

Type Aliases

Type Alias	Description
Any	Type that refers to any. Useful for bypass lint or type coverage checks. Please use only in circumstances that require it. See *this link*. Remarks Basically the same as TypeScript's built-in any. It's better to not use any.
Anything	Type that refers to any. Useful for bypass lint or type coverage checks. Please use only in circumstances that require it. See *this link*. Remarks Basically the same as TypeScript's built-in any. It's better to not use any.
Array	Type that represents an array with elements of type T. Example // MyArray is string[] type MyArray = Array<string>;
Arr	Alias for `Array`.
List	Alias for `Array`.
WritableArray	Alias for `Array`.
WritableArr	Alias for `Array`.
WritableList	Alias for `Array`.
ReadonlyArray	Type that represents a read-only array with elements of type T. Example // MyReadonlyArray is readonly string[] type MyReadonlyArray = ReadonlyArray<string>;
ReadonlyArr	Alias for `ReadonlyArray`.
ReadonlyList	Alias for `ReadonlyArray`.
Tuple	Type that represents a tuple, which is a fixed-length array of elements of type T. Example // MyTuple is [number, string] type MyTuple = Tuple<[number, string]>;
WritableTuple	Alias for `Tuple`.
ReadonlyTuple	Type that represents a read-only tuple, which is a fixed-length, immutable array of elements of type T. Example // MyReadonlyTuple is readonly [number, string] type MyReadonlyTuple = ReadonlyTuple<[number, string]>;
Class	Type that represents a class constructor that takes specified parameters types and returns an instance of a specified type. Example // C is a class // with constructor(id: number, name: string) // and {id: number, name: string} as instance and prototype type C = Class<[id: number, name: string], {id: number, name: string}>;
Falsy	Type that represents falsy value. This includes false, '', 0, 0n, null, undefined, and void.
Function	Type that represents a function that takes specified parameters types and returns a specified type. Example // MyFunction is (param_0: number, param_1: string) => string type MyFunction = Function<[number, string], string>;
Fn	Alias for `Function`.
AsyncFunction	Type that represents an async function that takes specified parameters types and returns a specified type. Example // MyAsyncFunction is (param_0: number, param_1: string) => Promise<string> type MyAsyncFunction = AsyncFunction<[number, string], string>;
AsyncFn	Alias for `AsyncFunction`.
NewableFunction	Type that represents a newable function that takes specified parameters types and returns a specified type. Example // MyNewableFunction is new (param_0: number, param_1: string) => string` type MyNewableFunction = NewableFunction<[number, string], string>;
NewableFn	Alias for `NewableFn`.
PositiveInfinity	Represents positive infinity in TypeScript as a constant value. Not a real type for javascript built-in Infinity or Number.POSITIVE_INFINITY.
NegativeInfinity	Represents negative infinity in TypeScript as a constant value. Not a real type for javascript built-in -Infinity or Number.NEGATIVE_INFINITY.
Infinity	Represents positive or negative infinity in TypeScript as a constant value. Not a real type for javascript built-in Infinity or Number.POSITIVE_INFINITY. Not a real type for javascript built-in -Infinity or Number.NEGATIVE_INFINITY.
NonNullish	Type that refers to any (non-null/undefined) value with zero or more properties. See this link. Example const example: NonNullish = true; // valid const example2: NonNullish = true as boolean | null; // invalid const example3: NonNullish = null || undefined; // invalid
Nullable	Type that allows a value to be T or null. Example const example: Nullable<string> = null; // valid const example2: Nullable<string> = undefined; // invalid
Nullish	Type that allows a value to be T, null, or undefined. Example const example: Nullish = null; // valid const example2: Nullish = undefined; // valid
ObjectGeneric	Extended TypeScript `Record` to define a generic object type. Example // ObjNumber is { [x: string]: number; [x: number]: number; [x: symbol]: number; } type ObjNumber = ObjectGeneric<number>; const Valid: ObjNumber = { a: 1, b: 2 }; const Invalid: ObjNumber = { a: '1', b: '2' }; // Type 'string' is not assignable to type 'number'
ObjectEmpty	Extended TypeScript `Record` to define a empty object type. Example // ObjEmpty is { [x: string]: never; [x: number]: never; [x: symbol]: never; } type ObjEmpty = ObjectEmpty; const Valid: ObjEmpty = {}; const Invalid: ObjEmpty = { a: 1 } // Type 'number' is not assignable to type 'never'
ObjectArrayLike	Extended TypeScript `Record` to define an object with number as key type. Example // ObjArrayLike is { [x: number]: string; } type ObjArrayLike = ObjectArrayLike<string>; const Valid: ObjArrayLike = { 0: 'first', 1: 'second' }; const Invalid: ObjArrayLike = { 0: 'first', a: 'second' }; // a is invalid key
Primitive	Type that represents any primitive value. This includes boolean, string, number, bigint, symbol, null, and undefined. Example const value1: Primitive = ""; // valid const value2: Primitive = {}; // invalid
Async	Built-in `Promise` with default type. Example // AsyncValue is Promise<string> type AsyncValue = Async<string>;
Undefinable	Type that allows a value to be T or undefined. Example const example: Undefinable<string> = undefined; // valid const example2: Undefinable<string> = null; // invalid
Void	Type that refers to void. Useful for bypass lint. Remarks Basically the same as TypeScript's built-in void. It's better to not use void outside a return type.