Javascript Countdown Clock every Saturday at 11AM

Question

I have a request to make that looks a little different than most the answers I found on here. I am looking for a Javascript countdown clock that repeats itself every Saturday at 11AM based on the server's clock, with the exception that the server is in CA, and the clock needs to be in EST. I forked this other clock as a start, however I am lost when it comes to creating a weekly schedule, instead of hard coded dates. Any help would be greatly appreciated. Thank you.

http://codepen.io/anon/pen/WrVXNE

function getTimeRemaining(endtime) {
  var t = Date.parse(endtime) - Date.parse(new Date());
  var seconds = Math.floor((t / 1000) % 60);
  var minutes = Math.floor((t / 1000 / 60) % 60);
  var hours = Math.floor((t / (1000 * 60 * 60)) % 24);
  var days = Math.floor(t / (1000 * 60 * 60 * 24));
  return {
    'total': t,
    'days': days,
    'hours': hours,
    'minutes': minutes,
    'seconds': seconds
  };
}

function initializeClock(id, endtime) {
  var clock = document.getElementById(id);
  var daysSpan = clock.querySelector('.days');
  var hoursSpan = clock.querySelector('.hours');
  var minutesSpan = clock.querySelector('.minutes');
  var secondsSpan = clock.querySelector('.seconds');

  function updateClock() {
    var t = getTimeRemaining(endtime);

    daysSpan.innerHTML = t.days;
    hoursSpan.innerHTML = ('0' + t.hours).slice(-2);
    minutesSpan.innerHTML = ('0' + t.minutes).slice(-2);
    secondsSpan.innerHTML = ('0' + t.seconds).slice(-2);

    if (t.total <= 0) {
      clearInterval(timeinterval);
    }
  }

  updateClock();
  var timeinterval = setInterval(updateClock, 1000);
}

var deadline = new Date(Date.parse(new Date()) + 15 * 24 * 60 * 60 * 1000);
initializeClock('clockdiv', deadline);

body{
	text-align: center;
	background: #00ECB9;
  font-family: sans-serif;
  font-weight: 100;
}

h1{
  color: #396;
  font-weight: 100;
  font-size: 40px;
  margin: 40px 0px 20px;
}

#clockdiv{
	font-family: sans-serif;
	color: #fff;
	display: inline-block;
	font-weight: 100;
	text-align: center;
	font-size: 30px;
}

#clockdiv > div{
	padding: 10px;
	border-radius: 3px;
	background: #00BF96;
	display: inline-block;
}

#clockdiv div > span{
	padding: 15px;
	border-radius: 3px;
	background: #00816A;
	display: inline-block;
}

.smalltext{
	padding-top: 5px;
	font-size: 16px;
}

<h1>Countdown Clock</h1>
<div id="clockdiv">
  <div>
    <span class="days"></span>
    <div class="smalltext">Days</div>
  </div>
  <div>
    <span class="hours"></span>
    <div class="smalltext">Hours</div>
  </div>
  <div>
    <span class="minutes"></span>
    <div class="smalltext">Minutes</div>
  </div>
  <div>
    <span class="seconds"></span>
    <div class="smalltext">Seconds</div>
  </div>
</div>

Answer 1

You can use this to get the next saturaday at 11am date:

function getNextSaturday() {
   var now = new Date();
   var nextSaturday = new Date();
   nextSaturday.setDate(now.getDate() + (6 - 1 - now.getDay() + 7) % 7 + 1);
   nextSaturday.setHours(11, 0, 0, 0);
   return nextSaturday;
}

And this to convert it to EST timezone:

function convertToEST(date){
    estOffset = -4.0 // -5 + 1 daylight savings
    utc = date.getTime() + (date.getTimezoneOffset() * 60000);
    return new Date(utc + (3600000 * estOffset));
}

All in all:

function getTimeRemaining(endtime) {
  var t = Date.parse(endtime) - Date.parse(new Date());
  var seconds = Math.floor((t / 1000) % 60);
  var minutes = Math.floor((t / 1000 / 60) % 60);
  var hours = Math.floor((t / (1000 * 60 * 60)) % 24);
  var days = Math.floor(t / (1000 * 60 * 60 * 24));
  return {
    'total': t,
    'days': days,
    'hours': hours,
    'minutes': minutes,
    'seconds': seconds
  };
}

function initializeClock(id, endtime) {
  var clock = document.getElementById(id);
  var daysSpan = clock.querySelector('.days');
  var hoursSpan = clock.querySelector('.hours');
  var minutesSpan = clock.querySelector('.minutes');
  var secondsSpan = clock.querySelector('.seconds');

  function updateClock() {
    var t = getTimeRemaining(endtime);

    daysSpan.innerHTML = t.days;
    hoursSpan.innerHTML = ('0' + t.hours).slice(-2);
    minutesSpan.innerHTML = ('0' + t.minutes).slice(-2);
    secondsSpan.innerHTML = ('0' + t.seconds).slice(-2);

    if (t.total <= 0) {
      clearInterval(timeinterval);
    }
  }

  updateClock();
  var timeinterval = setInterval(updateClock, 1000);
}

function getNextSaturday() {
   var now = new Date();
   var nextSaturday = new Date();
   nextSaturday.setDate(now.getDate() + (6 - 1 - now.getDay() + 7) % 7 + 1);
   nextSaturday.setHours(11, 0, 0, 0);
   return nextSaturday;
}

function convertToEST(date){
    estOffset = -5.0
    utc = date.getTime() + (date.getTimezoneOffset() * 60000);
    return new Date(utc + (3600000 * estOffset));
}

var deadline = getNextSaturday();
initializeClock('clockdiv', convertToEST(deadline));

body{
	text-align: center;
	background: #00ECB9;
  font-family: sans-serif;
  font-weight: 100;
}

h1{
  color: #396;
  font-weight: 100;
  font-size: 40px;
  margin: 40px 0px 20px;
}

#clockdiv{
	font-family: sans-serif;
	color: #fff;
	display: inline-block;
	font-weight: 100;
	text-align: center;
	font-size: 30px;
}

#clockdiv > div{
	padding: 10px;
	border-radius: 3px;
	background: #00BF96;
	display: inline-block;
}

#clockdiv div > span{
	padding: 15px;
	border-radius: 3px;
	background: #00816A;
	display: inline-block;
}

.smalltext{
	padding-top: 5px;
	font-size: 16px;
}

<h1>Countdown Clock</h1>
<div id="clockdiv">
  <div>
    <span class="days"></span>
    <div class="smalltext">Days</div>
  </div>
  <div>
    <span class="hours"></span>
    <div class="smalltext">Hours</div>
  </div>
  <div>
    <span class="minutes"></span>
    <div class="smalltext">Minutes</div>
  </div>
  <div>
    <span class="seconds"></span>
    <div class="smalltext">Seconds</div>
  </div>
</div>