configurewebpack的作用以及他的用法

configurewebpack中的配置型及详细的用法说明，chainWebpack的作用及其详细的用法和说明，vue.config.js中的常用的配置

```c++

参考：

'use strict'
const path = require('path')
const defaultSettings = require('./src/settings.js')

function resolve(dir) {
  return path.join(__dirname, dir)
}

const name = defaultSettings.title || '自学考试管理系统' // 标题

const port = 9527 // DEV端口

// 所有配置项说明都可以在https://cli.vuejs.org/config中找到
module.exports = {
  /**
   * 如果计划在子路径下部署站点，则需要设置publicPath，
   * 例如，Github页面。如果您计划将站点部署到https://foo.github.io/bar/，
   * 然后publicpath应设置为“/bar/”。
   * 在大多数情况下，请使用'/'！！！！
   * 详情：https://cli.vuejs.org/config/publicpath
   */
  publicPath: '/zikao',
  outputDir: 'dist',
  assetsDir: 'static',
  lintOnSave: process.env.NODE_ENV === 'development',
  productionSourceMap: false,
  devServer: {
    host: '0.0.0.0',
    port: port,
    open: true,
    overlay: {
      warnings: false,
      errors: true
    },
    // proxy: {
    //   [process.env.VUE_APP_BASE_API]: {
    //     // 后台接口
    //     target: `http://localhost:8080`,
    //     changeOrigin: true,
    //     pathRewrite: {
    //       ['^' + process.env.VUE_APP_BASE_API]: ''
    //     }
    //   }
    // },
    disableHostCheck: true
  },
  configureWebpack: {
    name: name,
    resolve: {
      alias: {
        '@': resolve('src')
      }
    }
  },
  chainWebpack(config) {
    config.plugins.delete('preload') // TODO: need test
    config.plugins.delete('prefetch') // TODO: need test

    // set svg-sprite-loader
    config.module
      .rule('svg')
      .exclude.add(resolve('src/icons'))
      .end()
    config.module
      .rule('icons')
      .test(/\.svg$/)
      .include.add(resolve('src/icons'))
      .end()
      .use('svg-sprite-loader')
      .loader('svg-sprite-loader')
      .options({
        symbolId: 'icon-[name]'
      })
      .end()

    // set preserveWhitespace
    config.module
      .rule('vue')
      .use('vue-loader')
      .loader('vue-loader')
      .tap(options => {
        options.compilerOptions.preserveWhitespace = true
        return options
      })
      .end()

    config
      // https://webpack.js.org/configuration/devtool/#development
      .when(process.env.NODE_ENV === 'development',
        config => config.devtool('cheap-source-map')
      )

    config
      .when(process.env.NODE_ENV !== 'development',
        config => {
          config
            .plugin('ScriptExtHtmlWebpackPlugin')
            .after('html')
            .use('script-ext-html-webpack-plugin', [{
            // `runtime` must same as runtimeChunk name. default is `runtime`
              inline: /runtime\..*\.js$/
            }])
            .end()
          config
            .optimization.splitChunks({
              chunks: 'all',
              cacheGroups: {
                libs: {
                  name: 'chunk-libs',
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  chunks: 'initial' // only package third parties that are initially dependent
                },
                elementUI: {
                  name: 'chunk-elementUI', // split elementUI into a single package
                  priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
                  test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
                },
                commons: {
                  name: 'chunk-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }
            })
          config.optimization.runtimeChunk('single')
        }
      )
  }
}