next.config.js

const path = require('path')
const glob = require('glob')

module.exports = {
  webpack(config) {
    config.module.rules.push(
      {
        test: /\.(css|scss)/,
        loader: 'emit-file-loader',
        options: {
          name: 'dist/[path][name].[ext]'
        }
      },
      {
        test: /\.(mov|mp4)$/,
        use: [
          {
            loader: 'file-loader',
            options: {
              name: '[name].[ext]'
            }
          }
        ]
      },
      {
        test: /\.css$/,
        use: ['babel-loader', 'raw-loader', 'postcss-loader']
      },
      {
        test: /\.s(a|c)ss$/,
        use: [
          'babel-loader',
          'raw-loader',
          'postcss-loader',
          {
            loader: 'sass-loader',
            options: {
              includePaths: ['styles', 'node_modules']
                .map(d => path.join(__dirname, d))
                .map(g => glob.sync(g))
                .reduce((a, c) => a.concat(c), [])
            }
          }
        ]
      }
    )
    return config
  },
  exportPathMap() {
    const paths = glob.sync('pages/**')
    const pages = paths
      .map(path => {
        path = path.replace(/^pages/, '')
        path = path.replace('index.js', '')
        path = path.replace('.js', '')

        if (path === '/_document') return null
        if (path === '/') return path

        path = path.replace(/\/$/, '')
        return path
      })
      .filter(Boolean)

    const pageMap = pages.reduce((map, page) => {
      map[page] = { page }
      return map
    }, {})

    return pageMap
  }
}