node-express-mongodb-jwt-rest-api-skeleton/app/controllers/cities/helpers/cityExists.js

Node.js express.js MongoDB JWT REST API - This is a basic API REST skeleton written on JavaScript using async/await. Great for building a starter web API for your front-end (Android, iOS, Vue, react, angular, or anything that can consume an API)

const City = require('../../../models/city')
const { buildErrObject } = require('../../../middleware/utils')

/**
 * Checks if a city already exists in database
 * @param {string} name - name of item
 */
const cityExists = (name = '') => {
  return new Promise((resolve, reject) => {
    City.findOne(
      {
        name
      },
      (err, item) => {
        if (err) {
          return reject(buildErrObject(422, err.message))
        }

        if (item) {
          return reject(buildErrObject(422, 'CITY_ALREADY_EXISTS'))
        }
        resolve(false)
      }
    )
  })
}

module.exports = { cityExists }