index.js

const meow = require('meow');
const isonline = require('is-online');
const readline = require('readline');
const fs = require('fs');

// Current iteration count
let iteration = 0;
// Number of times successfully connected to internet
let connectedTries = 0;

const cli = meow(`
  Usage
    $ is-online-stats <input>

  Options
    --wait, -w Number of minutes to wait between checks (Default: 10 minutes)
    --iterations, -i Number of iterations (Default: infinite)
    --timeout, -t Timeout in seconds to wait for a server to respond (Default: 2 seconds)
  `, {
    flags: {
      wait: {
        type: 'integer',
        alias: 'w',
        default: 10
      },
      iterations: {
        type: 'integer',
        alias: 'i',
        default: -1
      },
      timeout: {
        type: 'integer',
        alias: 't',
        default: 2
      },
      file: {
        type: 'string',
        alias: 'f',
        default: 'log.txt'
      }
    }
  });

// Number of iterations to try, -1 will cause it to continually run
const iterations = cli.flags.iterations;
// Amount of time to wait between checks
const waitTimeout = cli.flags.wait * 1000 * 60;
// Logfile for keeping track
let logFile = -1;

function next() {
  iteration++;
  // Check to see if we are online or not
  isonline({
    timeout: cli.flags.timeout * 1000
  }).then(online => {
    // Keep track of successful connections and log percentage to console
    connectedTries += online ? 1 : 0;
    readline.cursorTo(process.stdout, 0);
    process.stdout.write(((connectedTries / iteration) * 100) + '% up-time')
    // And keep track of each in file
    fs.writeSync(logFile, iteration + ',' + (online ? 1 : 0) + '\n');
    // If we are not done, will call the next one on the wait timeout
    if (iterations === -1 || iteration < iterations) {
      setTimeout(next, waitTimeout);
    } else {
      fs.closeSync(logFile);
    }
  });
}

try {
  logFile = fs.openSync(cli.flags.file, 'w');
  fs.writeSync(logFile, 'iteration,online\n');
  next();
} catch (err) {
  console.log('Failed due to err: %s', err);
  if (logFile) {
    fs.closeSync(logFile);
  }
}