How to have Global Variables on Express, Nodejs

const log4js = require('log4js')
const { Router } = require('express')

const router = Router()

const myfunc_set = async (req, res) =>{
  logger.info('myfunc_set')
  try {
    const val1 = req.query.val1
    req.app.set('value1', val1)
    res.send({'value1': val1})
  } catch (e){
  }
}

const myfunc_get = async (req, res) =>{
  logger.info('myfunc_get')
  try {
    res.send({'value1': req.app.get('value1')})
  } catch (e){
  }
}

router.route('/value1')
  .get(myfunc_get)
  .post(myfunc_set)