Snippet to display JS countdown timer on WooCommerce product page

countdown-timer.php

<?php

// Add this function to any hook listed here - https://www.businessbloomer.com/woocommerce-visual-hook-guide-single-product-page/

function delivery_countdown() {
	date_default_timezone_set('Europe/London');	// Specify preferred time zone
	$deadline = 12; // 0 = 12AM, 12 = 12PM, 23 = 11PM
	$isWeekend = null;
	$weekend = array('Saturday', 'Sunday');
	$weekdayDeadline = "Friday 12PM";
	
	if ( in_array( date("l"), $weekend ) || ( strtotime("now") > strtotime($weekdayDeadline) ) ) {
		$isWeekend = true;
	} else {
		$isWeekend = false;
	}
   
	if ( ! $isWeekend ) {
		echo '
		  <p><span id="delivery-countdown"></span></p>
		  <script>
			jQuery( function( $ ) {
			$(document).ready(function(){
				function countdownTimer() {
					let currentTime = new Date();
					let deadline = ' . $deadline . ';
					deadline -= 1;
					let hrs, mins, secs, hrsPrefix, minsPrefix, secsPrefix;
					if (currentTime.getHours() > deadline) {
						hrs = (deadline - currentTime.getHours()) + 24;
						if (currentTime.getDay() == 5) {
							hrs += 48;
						}
						if (currentTime.getDay() == 6) {
							hrs += 24;
						}
					} else {
						hrs = deadline - currentTime.getHours();
					}
					mins = 59 - currentTime.getMinutes();
					secs = 59 - currentTime.getSeconds();
					if (hrs == 1) {
						hrsPrefix = " hour ";
					} else {
						hrsPrefix = " hours ";
					}
					if (mins == 1) {
						minsPrefix = " minute ";
					} else {
						minsPrefix = " minutes ";
					}
					if (secs == 1) {
						secsPrefix = " second";
					} else {
						secsPrefix = " seconds";
					}
					timeLeft = hrs + hrsPrefix + mins + minsPrefix + secs + secsPrefix;
					$("#delivery-countdown").html(timeLeft);
				}
				setInterval(countdownTimer ,1000);
			});
		}); 
		  </script>
	   ';	
	}
}

?>