@boostpack/class

Utilities for working with classes in TypeScript.

Installation

npm install @boostpack/class

API

ClassConstructor<T>

Represents any class constructor (including abstract classes) that produces an instance of type T.

import { ClassConstructor } from '@boostpack/class';

function create<T>(ctor: ClassConstructor<T>, ...args: unknown[]): T {
  return new (ctor as new (...a: unknown[]) => T)(...args);
}

class UserService {}

const instance = create(UserService); // UserService

OptionalClassConstructor<T>

A class constructor that may be undefined. Useful for optional dependency injection or conditional class resolution.

import { OptionalClassConstructor } from '@boostpack/class';

function resolveOptional<T>(ctor: OptionalClassConstructor<T>): T | undefined {
  return ctor ? new (ctor as new () => T)() : undefined;
}

const Logger: OptionalClassConstructor<Console> = undefined;
resolveOptional(Logger); // undefined

OptionalClassInstance<C>

Conditionally resolves to InstanceType<C> if C is a constructable class, otherwise undefined. Works at the type level for generic programming.

import { OptionalClassInstance } from '@boostpack/class';

class Config {}

type A = OptionalClassInstance<typeof Config>; // Config
type B = OptionalClassInstance<string>;        // undefined

License

MIT