text: const path = require('path')
  
  module.exports = {
    mode: 'production',
    entry: './src/index.js',
    externals: {
      lodash: {
        commonjs: lodash,
        root: '_'//html <script>标签
      }
    },//不打包进去
    output: {
      path: path.resolve(__dirname, 'dist'),
      filename: 'library.js',
      library: 'root',
      libraryTarget: 'umd'
    }
  }