Nuxt/lib/builder/webpack/plugins/vue/util.mjs

import chalk from 'chalk'

const prefix = `[vue-server-renderer-webpack-plugin]`
export const warn = msg => console.error(chalk.red(`${prefix} ${msg}\n`)) // eslint-disable-line no-console
export const tip = msg => console.log(chalk.yellow(`${prefix} ${msg}\n`)) // eslint-disable-line no-console

export const validate = compiler => {
  if (compiler.options.target !== 'node') {
    warn('webpack config `target` should be "node".')
  }

  if (compiler.options.output && compiler.options.output.libraryTarget !== 'commonjs2') {
    warn('webpack config `output.libraryTarget` should be "commonjs2".')
  }

  if (!compiler.options.externals) {
    tip(
      'It is recommended to externalize dependencies in the server build for ' +
      'better build performance.'
    )
  }
}

export const onEmit = (compiler, name, hook) => {
  if (compiler.hooks) {
    // Webpack >= 4.0.0
    compiler.hooks.emit.tap(name,
      (compilation) => new Promise((resolve, reject) => {
        try {
          hook(compilation, resolve)
        } catch (e) {
          reject(e)
        }
      }))
  } else {
    // Webpack < 4.0.0
    compiler.plugin('emit', hook)
  }
}

export const isJS = (file) => /\.js(\?[^.]+)?$/.test(file)

export const isCSS = (file) => /\.css(\?[^.]+)?$/.test(file)