simple-obs-countdown/bin/countdown.js

Simple countdown timer script for OBS

#!/usr/bin/env node

const fs = require('fs');
const package = require('../package.json');

const program = require('commander');

const FRAME = 1 / 60;
const SECOND = 1;
const MINUTE = 60 * SECOND;
const HOUR = 60 * MINUTE;

program
  .version(package.version, '-v, --version');

program
  .arguments('<end> <file>')
  .alias('cd')
  .description('Write countdown clock until time to the given file')
  .action(action);


function getInterval(start, end) {
  let range = end - start;

  const interval = {
    range
  };

  const millis = Math.floor(range / 1000);
  if (millis < 0) {
    range = 0;
  } else {
    range = Math.floor(range / 1000) + 1;
  }

  interval.hour = Math.floor(range / HOUR);
  range %= HOUR;

  interval.minute = Math.floor(range / MINUTE);
  range %= MINUTE;

  interval.second = range

  return interval;
}


function action(end, file) {
  console.log(`Counting down until ${ end }`);

  const endTime = Date.parse(end);

  let timeString = '';

  const writeFile = (string) => new Promise((res, rej) => {
    fs.writeFile(file, string, (err) => {
      if (err) {
        return rej(err);
      }
      return res();
    });
  });

  const update = () => {
    const interval = getInterval(Date.now(), endTime);

    if (interval.range <= 0) {
      return writeFile('0:00')
      .then(() => new Promise((res) => setTimeout(res, 1000)))
      .then(() => writeFile(''))
      .then(() => {
        console.log('Countdown complete');
        process.exit(0);
      });
    }

    const newString = `${ interval.minute }:${ ('0' + interval.second).slice(-2) }`;
    if (newString !== timeString) {
      timeString = newString;
      return writeFile(timeString).then(() => setTimeout(update, FRAME));
    }

    setTimeout(update, FRAME);
  };

  update();
}

program.parse(process.argv);

module.exports = {
  getInterval,
  action
};