Element-UI二次开发后，如何正确集成到Vue项目中？并按需打包需要的文件？

Question

我下载了element-ui 2.15.4这个版本项目（二次开发），打包出来的lib 文件里面就一个js的压缩问题，但是我的vue项目里面node_modules>element-ui>lib 里面文件特别多，我怎么才能把element-ui 打包的文件在vue项目使用啊

直接替换lib 根本没有用，然后修改node_modules>element-ui>lib 也没有用,删除了cache

怎么修改wabpack.config.js 按需打包需要的js啊，

const path = require('path');
const ProgressBarPlugin = require('progress-bar-webpack-plugin');
const VueLoaderPlugin = require('vue-loader/lib/plugin');
const TerserPlugin = require('terser-webpack-plugin');

const config = require('./config');

module.exports = {
  mode: 'production',
  entry: {
    app: ['./src/index.js']
  },
  output: {
    path: path.resolve(process.cwd(), './lib'),
    publicPath: '/dist/',
    filename: 'index.js',
    chunkFilename: '[id].js',
    libraryTarget: 'umd',
    libraryExport: 'default',
    library: 'ELEMENT',
    umdNamedDefine: true,
    globalObject: 'typeof self !== \'undefined\' ? self : this'
  },
  resolve: {
    extensions: ['.js', '.vue', '.json'],
    alias: config.alias
  },
  externals: {
    vue: config.vue
  },
  optimization: {
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          output: {
            comments: false
          }
        }
      })
    ]
  },
  performance: {
    hints: false
  },
  stats: {
    children: false
  },
  module: {
    rules: [
      {
        test: /\.(jsx?|babel|es6)$/,
        include: process.cwd(),
        exclude: config.jsexclude,
        loader: 'babel-loader'
      },
      {
        test: /\.vue$/,
        loader: 'vue-loader',
        options: {
          compilerOptions: {
            preserveWhitespace: false
          }
        }
      }
    ]
  },
  plugins: [
    new ProgressBarPlugin(),
    new VueLoaderPlugin()
  ]
};