get battery info with node.js

node-sample.js

const http = require('http');
const PORT = Number(process.argv[2]) || 8080;
const child_process = require('child_process');

const Routes = {
  BATTERY: /\/battery\/?/
};

const Status = {
  NOT_FOUND: 404,
  NOT_FOUND_MSG: '404 - Resource Not found',
  OK: 200,
  OK_MSG: '200 - Success',
  BATTERY_ERROR: 500,
  BATTERY_ERROR_MSG: '500 - Battery Error'
};

const renderResult = (response, data) => {
  response.writeHead(data.status, {'Content-Type': 'application/json'});
  response.write(JSON.stringify(data));
  response.end();
};

const switchConfigForCurrentOS = () => {
  switch (process.platform) {
    case 'linux':
      return {
        command: 'upower -i /org/freedesktop/UPower/devices/battery_BAT0 | grep -E "state|time to empty|to full|percentage"',
      };
    case 'darwin':
      //MAC
      return {
        command: 'pmset -g batt | egrep "([0-9]+\%).*" -o',
      };
    case 'win32':
      return {
        command: 'WMIC Path Win32_Battery',
      };
    default:
      return {
        command: '',
      };
  }
};

const getBatteryStatus = (response, config) => {
  child_process.exec(config.command, (err, stdout, stderr) => {
    if (err) {
      console.error('child_process failed with error code: ' + err.code);
      renderResult(response, {
        status: Status.BATTERY_ERROR,
        message: stderr
      });
    } else {
      try {
        renderResult(response, {
          status: Status.OK,
          data: stdout
        });
      } catch (e) {
        console.error(e);
        renderResult(response, {
          status: Status.BATTERY_ERROR,
          message: Status.BATTERY_ERROR_MSG
        });
      }
    }
  });
};

const server = http.createServer((request, response) => {
  const requestUrl = request.url;
  const config = switchConfigForCurrentOS();
  if (Routes.BATTERY.test(requestUrl)) {
    getBatteryStatus(response, config);
    console.log('--- ', requestUrl);
  } else {
    renderResult(response, {
      status: Status.NOT_FOUND,
      message: Status.NOT_FOUND_MSG
    });
  }
}).listen(PORT);
console.log('Server running on port ' + PORT);