project-root-directory/index.js

find the project root

/* eslint-env node */

const path = require('path')
const resolveFrom = require('resolve-from')

module.exports = process.env.APP_ROOT_PATH
  ? path.resolve(process.env.APP_ROOT_PATH)
  : resolveFrom(__dirname, 'resolve-from').split(path.sep + 'node_modules' + path.sep)[0]