oidc-provider/lib/helpers/type_validators.js

OAuth 2.0 Authorization Server implementation for Node.js with OpenID Connect

const hasPrototype = (target) => target.prototype !== null && typeof target.prototype === 'object';

const isContructor = (fn) => fn.constructor instanceof Function
  && fn.constructor.name !== undefined;

export default (constructable) => constructable instanceof Function
      && hasPrototype(constructable)
      && isContructor(constructable.constructor);