JSFiddle - React, Tailwind, and code Playground

HTML

<p id="wbtime" align="center"></p>

JavaScript

var rec = 120;
		var einit = 205;
		
function twodigits(d){
    return d.toString().replace(/^(.)$/,'0$1')
}

function EventCD() {
    
    var date = new Date;
        var h = date.getHours();
        var m = date.getMinutes();
        var s= date.getSeconds();
        var Hcour = (h * 60) + m;
		var Affichage = "";
 		while (Hcour > (einit + 15)) {
			einit = einit + rec;
		}
		if (Hcour < einit) {
			Timeto = einit - Hcour;
			HeureCD = parseInt(Timeto / 60);
            MinCD = (Timeto - (HeureCD * 60) - 1);
            SecCD= (59 - s);
			Affichage = "Temps avant apparition "+ twodigits(HeureCD) +" H "+ twodigits(MinCD) +" min "+ twodigits(SecCD) +" sec.";
		}
		else {
		Affichage = "En cours...";
		}
    document.getElementById('wbtime').innerHTML=Affichage
	timerID = setTimeout(EventCD,1000);
}
EventCD();