demo.js

/**
 * Particleground demo
 * @author Jonathan Nicol - @mrjnicol
 */

document.addEventListener('DOMContentLoaded', function () {
  particleground(document.getElementById('particles'), {
    dotColor: '#000',
    lineColor: '#000'
  });
  var intro = document.getElementById('intro');
  intro.style.marginTop = - intro.offsetHeight / 2 + 'px';
}, false);

const second = 1000,
      minute = second * 60,
      hour = minute * 60,
      day = hour * 24;

let countDown = new Date('Feb 29, 2020 00:00:00').getTime(),
    x = setInterval(function() {

      let now = new Date().getTime(),
          distance = countDown - now;

        document.getElementById('days').innerText = Math.floor(distance / (day)),
        document.getElementById('hours').innerText = Math.floor((distance % (day)) / (hour)),
        document.getElementById('minutes').innerText = Math.floor((distance % (hour)) / (minute)),
        document.getElementById('seconds').innerText = Math.floor((distance % (minute)) / second);

      //do something later when date is reached
      //if (distance < 0) {
      //  clearInterval(x);
      //  'IT'S MY BIRTHDAY!;
      //}

    }, second)
/*
// jQuery plugin example:
$(document).ready(function() {
  $('#particles').particleground({
    dotColor: '#5cbdaa',
    lineColor: '#5cbdaa'
  });
  $('.intro').css({
    'margin-top': -($('.intro').height() / 2)
  });
});
*/