function pad(n, len) { // leading 0's
    var s = n.toString();
    return (new Array( (len - s.length + 1) ).join('0')) + s;
  };

function countDown() {
    var now = new Date();
    var targetDay = 4; // Thursday (4) is the target day
    var target = 0; // Hour of the day to cutoff (0 for midnight)
    var days = 0, hrs = 0, mins = 0, secs = 0;

    //--> Day logic
    if(now.getDay() < targetDay - 1) {
        days = targetDay - now.getDay() - 1;
    }
    else if(now.getDay() > targetDay) {
        days = 8 - now.getDay() + targetDay;
    }
    //<-- Day logic

    // Countdown logic
    if (now.getHours() < target) {
        hrs = (target - 1) - now.getHours();
        if (hrs < 0) hrs = 0;
        mins = 59 - now.getMinutes();
        if (mins < 0) mins = 0;
        secs = 59 - now.getSeconds();
        if (secs < 0) secs = 0;
    }
    else if (now.getHours() > target) {
        hrs = 24 - now.getHours() + (target - 1);
        if (hrs < 0) hrs = 0;
        mins = 59 - now.getMinutes();
        if (mins < 0) mins = 0;
        secs = 59 - now.getSeconds();
        if (secs < 0) secs = 0;
    }
    else { // It's time!
        document.getElementById('countdownTimer').innerHTML = "It's time!";
    }
}

// Run immediately to get rid of delay
countDown();

// Run every second to update time remaining
if (document.getElementById('countdownTimer')) {
  var timerRunning = setInterval(
    function() {
      countDown();
    }, 1000
  );
}