timeLeft.js

function dateToSeconds(date) {
    const dateTime = new Date(date);
    return dateTime.getTime() / 1000;
}

function getDateMocked() {
    const date = new Date();

    date.setHours(17);
    date.setMinutes(0);
    date.setSeconds(0);

    return date;
}

function secondsToString(seconds) {
    const secondsInOneDay = 86400;
    const secondsInOneHour = 3600;
    const secondsInOneMinute = 60;

    const days = Math.floor(seconds / secondsInOneDay);
    const hours = Math.floor((seconds % secondsInOneDay) / secondsInOneHour);
    const minutes = Math.floor(((seconds % secondsInOneDay) % secondsInOneHour) / secondsInOneMinute);
    const secondsLeft = Math.floor(((seconds % secondsInOneDay) % secondsInOneHour) % secondsInOneMinute);

    return `${days}:${hours}:${minutes}:${secondsLeft}`;
}

const currentTimeInSeconds = dateToSeconds(new Date());
const serverTimeInSeconds = dateToSeconds(getDateMocked()); // TODO: Change this to the server time or something else.

const distanceBetweenTimes = serverTimeInSeconds - currentTimeInSeconds;

function getTimeLeft() {
    return secondsToString(distanceBetweenTimes);
}

console.log(`${distanceBetweenTimes} seconds left.`);

console.log(getTimeLeft());