This is a Next.js project bootstrapped with create-next-app.

description

once run function in next js with not custom server

run server

1. npm ci
2. npm run build
3. npm start

example run server - terminal

[changed console!] undefined [expected]: undefined // before run next
[changed console!] ready - started server on 0.0.0.0:3000, url: http://localhost:3000 // next run
[changed console!] info - Loaded env from **\next-init-function\.env // next run
[changed console!] run start // after run next
[changed console!] Hello!! [expected]: Hello!! // after run next
[changed console!] [in ServerSideProps] is console changed? // after run next (enter root page)

Read the app.js file

import changeConsole from './init/changeConsole'

// before next loading

changeConsole()
console.log(process.env.ENV_TEST, '[expected]: undefined') // undefined

// after next loading

const command = process.argv[2]
if (['dev', 'start'].includes(command)) {
  require('./node_modules/next/dist/bin/next')
  check(init)
}

// function
// function
// function

// next loading check
/** @param {Function} fn */
function check(fn) {
  setTimeout(() => {
    if (!('LOAD_CHECK' in process.env)) {
      setTimeout(check, 0, fn)
      return
    }
    fn()
  }, 50)
}

// after init function
function init() {
  switch (command) {
    case 'dev': {
      // here dev script
      console.log('run dev')
      break
    }
    case 'start': {
      // here start script
      console.log('run start')
      break
    }
  }
  // commons script
  console.log(process.env.ENV_TEST, '[expected]: Hello!!') // 'Hello!!'
}