JSFiddle - React, Tailwind, and code Playground

HTML

<div id="deliveryTimer">
<span id="countdownTimer">Just checking the time...</span>
</div>

JavaScript

var timerRunning = setInterval(



        function countDown() {

            var target = 14.5; // This is the cut-off point
			
            var now = new Date();

            

            //Put this in a variable for convenience

            var weekday = now.getDay();
			var despatchday = 'TODAY!';
			
			
			if(weekday == 0){//Sunday? Add 24hrs

                target += 24;

				despatchday='on Monday';

            }//keep this before the saturday, trust me :>

            

            if(weekday == 6){//It's Saturday? Add 48hrs

                target += 48;

				despatchday='on Monday';

            }

			

			if((weekday == 5) && (now.getHours() > target) && (now.getHours() <= 24) ){

				target += 72;

				despatchday='on Monday';

            }

  
            //If between Monday and Friday, 
            //check if we're past the target hours, 
            //and if we are, abort.
            if((weekday>=1 ) && (weekday<=5)){

                if ((now.getHours() > target) && (now.getHours() <= 24)) { //stop the clock

                    target += 24;

                    despatchday = 'tomorrow';

                }else if (now.getHours() > target) { //stop the clock

                    return 0;

                    despatchday = 'today';

                }                
            }

            

			var hrs = (target) - now.getHours();
            if (hrs < 0) hrs = 0;
            var mins = 59 - now.getMinutes();
            if (mins < 0) mins = 0;
            var secs = 59 - now.getSeconds();
            if (secs < 0) secs = 0;


			var str ='Order in the next ' + hrs + 'hrs ' + mins + 'mins ' + secs + 'secs for despatch ' + despatchday;

            document.getElementById('countdownTimer').innerHTML = str;

            

        }, 1000

    );