rsnext/packages/next/bin/next.ts

#!/usr/bin/env node
import * as log from '../build/output/log'
import arg from 'next/dist/compiled/arg/index.js'
import { NON_STANDARD_NODE_ENV } from '../lib/constants'
;['react', 'react-dom'].forEach((dependency) => {
  try {
    // When 'npm link' is used it checks the clone location. Not the project.
    require.resolve(dependency)
  } catch (err) {
    console.warn(
      `The module '${dependency}' was not found. Next.js requires that you include it in 'dependencies' of your 'package.json'. To add it, run 'npm install ${dependency}'`
    )
  }
})

const defaultCommand = 'dev'
export type cliCommand = (argv?: string[]) => void
const commands: { [command: string]: () => Promise<cliCommand> } = {
  build: () => Promise.resolve(require('../cli/next-build').nextBuild),
  start: () => Promise.resolve(require('../cli/next-start').nextStart),
  export: () => Promise.resolve(require('../cli/next-export').nextExport),
  dev: () => Promise.resolve(require('../cli/next-dev').nextDev),
  lint: () => Promise.resolve(require('../cli/next-lint').nextLint),
  telemetry: () =>
    Promise.resolve(require('../cli/next-telemetry').nextTelemetry),
  info: () => Promise.resolve(require('../cli/next-info').nextInfo),
}

const args = arg(
  {
    // Types
    '--version': Boolean,
    '--help': Boolean,
    '--inspect': Boolean,

    // Aliases
    '-v': '--version',
    '-h': '--help',
  },
  {
    permissive: true,
  }
)

// Version is inlined into the file using taskr build pipeline
if (args['--version']) {
  console.log(`Next.js v${process.env.__NEXT_VERSION}`)
  process.exit(0)
}

// Check if we are running `next <subcommand>` or `next`
const foundCommand = Boolean(commands[args._[0]])

// Makes sure the `next --help` case is covered
// This help message is only showed for `next --help`
// `next <subcommand> --help` falls through to be handled later
if (!foundCommand && args['--help']) {
  console.log(`
    Usage
      $ next <command>

    Available commands
      ${Object.keys(commands).join(', ')}

    Options
      --version, -v   Version number
      --help, -h      Displays this message

    For more information run a command with the --help flag
      $ next build --help
  `)
  process.exit(0)
}

const command = foundCommand ? args._[0] : defaultCommand
const forwardedArgs = foundCommand ? args._.slice(1) : args._

if (args['--inspect'])
  throw new Error(
    `--inspect flag is deprecated. Use env variable NODE_OPTIONS instead: NODE_OPTIONS='--inspect' next ${command}`
  )

// Make sure the `next <subcommand> --help` case is covered
if (args['--help']) {
  forwardedArgs.push('--help')
}

const defaultEnv = command === 'dev' ? 'development' : 'production'

const standardEnv = ['production', 'development', 'test']

if (process.env.NODE_ENV) {
  const isNotStandard = !standardEnv.includes(process.env.NODE_ENV)
  const shouldWarnCommands =
    process.env.NODE_ENV === 'development'
      ? ['start', 'build']
      : process.env.NODE_ENV === 'production'
      ? ['dev']
      : []

  if (isNotStandard || shouldWarnCommands.includes(command)) {
    log.warn(NON_STANDARD_NODE_ENV)
  }
}

;(process.env as any).NODE_ENV = process.env.NODE_ENV || defaultEnv

// Make sure commands gracefully respect termination signals (e.g. from Docker)
process.on('SIGTERM', () => process.exit(0))
process.on('SIGINT', () => process.exit(0))

commands[command]()
  .then((exec) => exec(forwardedArgs))
  .then(() => {
    if (command === 'build') {
      // ensure process exits after build completes so open handles/connections
      // don't cause process to hang
      process.exit(0)
    }
  })

if (command === 'dev') {
  const { CONFIG_FILES } = require('../shared/lib/constants')
  const { watchFile } = require('fs')

  for (const CONFIG_FILE of CONFIG_FILES) {
    watchFile(`${process.cwd()}/${CONFIG_FILE}`, (cur: any, prev: any) => {
      if (cur.size > 0 || prev.size > 0) {
        console.log(
          `\n> Found a change in ${CONFIG_FILE}. Restart the server to see the changes in effect.`
        )
      }
    })
  }
}