How to use webpack-dev-server

server.listen(8081,"0.0.0.0",function (err) {
  if(err)
  {
    console.log(err);
  }
})

const devServer = new WebpackDevServer(compiler, serverConfig);
devServer.listen(port, HOST, err => {
 if (err) {
  return console.log(err);
  devServer.close();
  process.exit();
 });

const devSocket = {
 warnings: warnings =>
  devServer.sockWrite(devServer.sockets, 'warnings', warnings),
 errors: errors =>
  devServer.sockWrite(devServer.sockets, 'errors', errors),
};
const devServer = new WebpackDevServer(compiler, serverConfig);
devServer.listen(port, HOST, err => {
 if (err) {
  return console.log(err);
  devServer.close();
  process.exit();
 });

const devSocket = {
  warnings: warnings =>
    devServer.sockWrite(devServer.sockets, 'warnings', warnings),
  errors: errors =>
    devServer.sockWrite(devServer.sockets, 'errors', errors),
};
const devServer = new WebpackDevServer(compiler, serverConfig);
devServer.listen(port, HOST, err => {
  if (err) {
    return console.log(err);
    devServer.close();
    process.exit();
  });

new WebpackDevServer(webpack(webpackConfig), {
 contentBase: [ config.get('buildDirectory'), '/' ].join(''),
 headers: { 'Access-Control-Allow-Origin': '*' },
 historyApiFallback: true,
 hot: true,
 noInfo: false,
 publicPath: webpackConfig.output.publicPath,
 proxy: {
  '*': 'http://' + host + ':' + appPort
 }
}).listen(devServerPort, host, function (err) {
 if (err) {
  console.log(err);
 }

 console.log('Webpack Dev Server running at ' + host + ':' + devServerPort);
});

new WebpackDevServer(webpack(WebpackConfig), WebpackConfig.devServer)
  .listen(WebpackConfig.port, 'localhost', (err) => {
    if (err) {
      console.log(err);
    }
    console.log('WebpackDevServer listening at localhost:' + WebpackConfig.port);
    console.log('Opening your system browser...');
    open('http://localhost:' + WebpackConfig.port + '/webpack-dev-server/');
  });

new WebpackDevServer(webpack(config), {
 hot: true,
 stats: {
  colors: true
 }
}).listen(3000, 'localhost', function (err) {
 if (err) {
  console.log(err);
 }

 console.log('Listening at localhost:3000');
});

new WebpackDevServer(webpack(config), {
 publicPath: config.output.publicPath,
 hot: true,
 historyApiFallback: true
}).listen(3000, 'localhost', function (err, result) {
 if (err)
  console.log(err)
 console.log('Listening at localhost:3000')
})

new WebpackDevServer(webpack(config), {
 contentBase: path.join(__dirname, './dist'),
 publicPath: config.output.publicPath,
 historyApiFallback: true,
 hot: true,
 stats: {
  colors: true
 }
}).listen(3000, 'localhost', function (err) {
 if (err) console.log(err);
 console.log('Listening at localhost:3000');
});

new WebpackDevServer(webpack(config), _.assign({}, config.devServer, otherConfig))
.listen(3000, 'localhost', function (err) {
 if (err) {
  console.log(err);
 }

 console.log('Listening at localhost:3000');
});

const devSocket = {
 warnings: warnings =>
  devServer.sockWrite(devServer.sockets, 'warnings', warnings),
 errors: errors =>
  devServer.sockWrite(devServer.sockets, 'errors', errors),
};
const devServer = new WebpackDevServer(compiler, serverConfig);
devServer.listen(port, HOST, err => {
 if (err) {
  return console.log(err);
  devServer.close();
  process.exit();
 });

const devSocket = {
  warnings: warnings =>
    devServer.sockWrite(devServer.sockets, 'warnings', warnings),
  errors: errors =>
    devServer.sockWrite(devServer.sockets, 'errors', errors),
};
const devServer = new WebpackDevServer(compiler, serverConfig);
devServer.listen(port, HOST, err => {
  if (err) {
    return console.log(err);
    devServer.close();
    process.exit();
  });

new WebpackDevServer(webpack(config), {
 publicPath: config.output.publicPath,
 hot: true,
 historyApiFallback: true
}).listen(3000, 'localhost', function (err, result) {
 if (err) {
  console.log(err);
 }

 console.log('Listening at localhost:3000');
});

new WebpackDevServer(webpack(config), {
 publicPath: config.output.publicPath,
 hot: true,
 historyApiFallback: true
}).listen(3001, 'localhost', function (err, result) {
 if (err) {
  console.log(err);
 }

 console.log('Listening at localhost:3001');
});

new WebpackDevServer(webpack(config), {
 publicPath: config.output.publicPath,
 hot: true,
 historyApiFallback: true
}).listen(9000, 'localhost', function (err, result) {
 if (err) {
  console.log(err);
 }

 console.log('Listening at localhost:9000');
});