Survey/quiz time limit

Good morning,
I am trying to set a 45-minute time limit for a survey/quiz, after which a user is automatically taken to the end of the survey. I came across the code below in another discussion, but the timer stops counting down when I move away from the page, and so, it does not count time spent on the survey accurately. Is there a way to set the time limit and keep track of time, even if the user is away from the survey page? Perhaps, there is a simpler way to accomplish this that I am not seeing.
Qualtrics.SurveyEngine.addOnload(function()
{
   var headerCont = document.createElement("div");  
 headerCont.className = "header-cont";  
 headerCont.id = "header_container";  
 var header = document.createElement("div");  
 header.className = "header"  
 header.id = "header_1";  
 var timer = document.createElement("div");  
 timer.className = "timer";  
 timer.id = "timer_1";  
 timer.innerHTML = "Time Remaining: 45:00"; 
 headerCont.appendChild(header);  
 header.appendChild(timer);  
 document.body.insertBefore(headerCont, document.body.firstChild);
function startTimer(duration, display) {  
  var timer = duration, minutes, seconds;  
  var myTimer = setInterval(function() {  
   minutes = parseInt(timer / 60, 10)  
   seconds = parseInt(timer % 60, 10);  
   minutes = minutes < 10 ? "0" + minutes : minutes;  
   seconds = seconds < 10 ? "0" + seconds : seconds;  
   var text = ('innerText' in display)? 'innerText' : 'textContent';
  display[text] = minutes + ":" + seconds;  
   if (--timer < 0) {  
    clearInterval(myTimer);  
    timeOver();   
   }  
  }, 1000);  
 }  
 var timerSeconds = 2700,  
 display = document.querySelector('#time');  
 startTimer(timerSeconds, display);  
 var timeOver = function() {  
     document.getElementById("timer_1").innerHTML = "Time is up.";

Qualtrics.SurveyEngine.setEmbeddedData("blockTimeFlag", "1");   
$('NextButton').click();
}