Server Side Timer

Question

<script>
	function viewnext()
	{
		var kk =document.getElementById('timer').value;
		var end_time ="2023-07-16 12:22:36";
		$.ajax({
					type: "POST",
					url: "server_side_timer_ajax.php",
					data:'end_time='+end_time,
					success: function(msg){
							
					if(msg==1)
					{
						alert("Please wait upto specified time limit");		
					}				
					else
				{
			if(12 < 17-1)
			{	
		       window.location="downloadable_student.php?id=8080&kd=MTM=";
			}
			else{	
					alert("Thanks, you have completed course successfully. Kindly submit your valuable feedback for further enrichments");
					window.open("feedback_student.php?id=8080",'_self');
				}
				}		
			},	
		});
		}
		function viewprev()
		{
			if(12 >0)
			{
			window.location="downloadable_student.php?id=8080&kd=MTE=";
			}
			else
			{
				alert("No Previous record available..");
			}
		}
	</script>

I am pursuing a course which contains slides to move on to next slide only after the timer value goes to zero and they have configured a end time variable only after that timer we can move on to the next slide. Kindly help to reoslve the issue