访客离开网站后，继续倒数计时器

Question

My timer starts on window load. After a visitor closes my website page the timer pauses. If the visitor opens the same page (with timer) after 10 hours, the timer starts from the same time where it had paused earlier.

I want to create a 3 hour timer that starts when website page is loaded and that keeps ticking in the background even if the visitor is not currently visiting my website page.

I wish to redirect the visitor to another page say "amazon.com" after this 3 hour timer has expired, if he visits the website AFTER 3 hours.

 function countdown() { time = parseInt(localStorage.time); if(isNaN(time) || time > (38 * 60)) { //alert("An error occured: time left variable is corrupted, resetting timer"); localStorage.time = 38 * 60; countdown(); return null; } if(time <= 0) { alert("Your Timer Has Run Out! We Still Got 2 Discount Copies Left, Hurry Up!"); return null; } var timers = document.getElementsByClassName('timeleft'); Array.prototype.forEach.call(timers, function(timer) { timer.innerText = formatTime(time); }) time--; localStorage.time = time; setTimeout('countdown()', 1000); } function formatTime(time) { minutes = Math.floor(time / 60); seconds = time - minutes * 60; if(String(seconds).length == 1) { return String(minutes) + ":0" + String(seconds); } return String(minutes) + ":" + String(seconds); } window.onload = function() { countdown(); } 

 <font size="+34"><div class="timeleft"></div></font> 

Answer 1

I think you can just store the start time in localStorage , and compare it to the current time whenever the page is loaded:

function startOrRedirect () {
  const startTime = localStorage.getItem('startTime')

  if (startTime) {
    const date1 = new Date(parseInt(startTime))
    const date2 = new Date()
    const hours = Math.abs(date1 - date2) / 36e5;

    if (hours >= 3) {
      redirect()
    }
  } else {
    localStorage.setItem('startTime', Date.now)
    setTimeout(redirect, 1000 * 60 * 60)
  }
}

function redirect () {
  window.location = 'https://amazon.com'
}

window.onload = startOrRedirect