artesanias/node_modules/is-npm/index.js

'use strict';

const userAgent = process.env.npm_config_user_agent;
const isYarn = Boolean(userAgent && userAgent.startsWith('yarn'));
const isNpm = Boolean(userAgent && userAgent.startsWith('npm'));

module.exports.isNpmOrYarn = isNpm || isYarn;
module.exports.isNpm = isNpm;
module.exports.isYarn = isYarn;