code: function build(previousFileSizes) {
      let packText = userDevConfig ? '启动测试环境打包编译...' : '启动生产环境打包压缩...';
      let startTime = Date.now();
      let timer;
      let logProgress = function(stop) {
          var text = packText + '已耗时：' + ((Date.now() - startTime) / 1000).toFixed(3) + 's';
  
          if (stop) {
              clearTimeout(timer);
              spinner.succeed(chalk.green(text));
          } else {
              spinner.text = chalk.cyan(text);
  
              timer = setTimeout(logProgress, 100);
          }
      };
  
      clearConsole();
      logProgress();
  
      let compiler = webpack(config);
  
      return new Promise((resolve, reject) => {
          compiler.run((err, stats) => {
              let messages;
  
              logProgress(true); // 停止
              console.log();
  
              if (err) {
                  if (!err.message) {
                      return reject(err);
                  }
  
                  messages = formatWebpackMessages({
                      errors: [err.message],
                      warnings: []
                  });
              } else {
                  messages = formatWebpackMessages(stats.toJson({ all: false, warnings: true, errors: true }));
              }
  
              if (messages.errors.length) {
                  if (messages.errors.length > 1) {
                      messages.errors.length = 1;
                  }
  
                  return reject(new Error(messages.errors.join('\n\n')));
              }
  
              const resolveArgs = {
                  stats,
                  previousFileSizes,
                  warnings: messages.warnings
              };
  
              return resolve(resolveArgs);
          });
      });
  }
docs: Create the production build and print the deployment instructions.