rsnext/packages/next/cli/next-dev.ts

#!/usr/bin/env node
import { resolve, join } from 'path'
import arg from 'next/dist/compiled/arg/index.js'
import { existsSync } from 'fs'
import startServer from '../server/lib/start-server'
import { printAndExit } from '../server/lib/utils'
import { startedDevelopmentServer } from '../build/output'
import { cliCommand } from '../bin/next'

const nextDev: cliCommand = argv => {
  const args = arg(
    {
      // Types
      '--help': Boolean,
      '--port': Number,
      '--hostname': String,

      // Aliases
      '-h': '--help',
      '-p': '--port',
      '-H': '--hostname',
    },
    { argv }
  )

  if (args['--help']) {
    // tslint:disable-next-line
    console.log(`
      Description
        Starts the application in development mode (hot-code reloading, error
        reporting, etc)

      Usage
        $ next dev <dir> -p <port number>

      <dir> represents where the compiled folder should go.
      If no directory is provided, the folder will be created in the current directory.
      You can set a custom folder in config https://github.com/zeit/next.js#custom-configuration.

      Options
        --port, -p      A port number on which to start the application
        --hostname, -H  Hostname on which to start the application
        --help, -h      Displays this message
    `)
    process.exit(0)
  }

  const dir = resolve(args._[0] || '.')

  // Check if pages dir exists and warn if not
  if (!existsSync(dir)) {
    printAndExit(`> No such directory exists as the project root: ${dir}`)
  }

  const port = args['--port'] || 3000
  const appUrl = `http://${args['--hostname'] || 'localhost'}:${port}`

  startedDevelopmentServer(appUrl)

  startServer({ dir, dev: true }, port, args['--hostname'])
    .then(async app => {
      await app.prepare()
    })
    .catch(err => {
      if (err.code === 'EADDRINUSE') {
        let errorMessage = `Port ${port} is already in use.`
        const pkgAppPath = require('find-up').sync('package.json', {
          cwd: dir,
        })
        const appPackage = require(pkgAppPath)
        if (appPackage.scripts) {
          const nextScript = Object.entries(appPackage.scripts).find(
            scriptLine => scriptLine[1] === 'next'
          )
          if (nextScript) {
            errorMessage += `\nUse \`npm run ${
              nextScript[0]
            } -- -p <some other port>\`.`
          }
        }
        // tslint:disable-next-line
        console.error(errorMessage)
      } else {
        // tslint:disable-next-line
        console.error(err)
      }
      process.nextTick(() => process.exit(1))
    })
}

export { nextDev }