npm-check-updates/build/src/types/GroupFunction.d.ts

Find newer versions of dependencies than what your package.json allows

import { SemVer } from 'semver-utils';
import { UpgradeGroup } from './UpgradeGroup';
/** Supported function for the --group options. */
export type GroupFunction = (packageName: string, defaultGroup: UpgradeGroup, currentVersionSpec: SemVer[], upgradedVersionSpec: SemVer[], upgradedVersion: SemVer | null) => UpgradeGroup | string;