require('os').networkInterfaces()[Object.keys(require('os').networkInterfaces())[0]][1].address + ':8080'　

vue.config.js

module.exports = {
  lintOnSave: false, // 是否開啟eslint儲存檢測，有效值：ture | false | 'error'
  publicPath: '',
  outputDir: process.env.outputDir,
  devServer: {
    public: require('os').networkInterfaces()[Object.keys(require('os').networkInterfaces())[0]][1].address + ':8080',
 

    disableHostCheck: true,
    open: true,
    proxy: {
      '/api': {
        target: 'http://xxx.com',
        pathRewrite: {'^/api' : ''},
        changeOrigin: true,    
        secure: false,   
      },
    }
  },
};

方法二：

node 14 之後的

const os = require('os');
/**
 * 獲取當前機器的ip地址
 */
 function getIpAddress() {
  let ifaces = os.networkInterfaces()
  for (let dev in ifaces) {
      let iface = ifaces[dev]
      for (let i = 0; i < iface.length; i++) {
          let { family, address, internal } = iface[i]
          if (family === 'IPv4' && address !== '127.0.0.1' && !internal) {
              return address
          }
      }
  }
}

　vue.config.js

const os = require('os');
/**
 * 獲取當前機器的ip地址
 */
 function getIpAddress() {
  let ifaces = os.networkInterfaces()
  for (let dev in ifaces) {
      let iface = ifaces[dev]
      for (let i = 0; i < iface.length; i++) {
          let { family, address, internal } = iface[i]
          if (family === 'IPv4' && address !== '127.0.0.1' && !internal) {
              return address
          }
      }
  }
}

module.exports = {
  lintOnSave: false, // 是否開啟eslint儲存檢測，有效值：ture | false | 'error'
  publicPath: '',
  outputDir: process.env.outputDir,
  devServer: {
    public: getIpAddress() + ':8080'
 
,
    disableHostCheck: true,
    open: true,
    proxy: {
      '/api': {
        target: 'http://mh.885505.com',
        pathRewrite: {'^/api' : ''},
        changeOrigin: true,    
        secure: false,   
      },
    }
  },
};

　效果：

 注： 我之前用的是node 8、 node 12  用的第一種方法，後來升級node 14  執行時報錯了 找不到 address ， 方法二可以；