JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<div id='countdown'></div>
<input type="button" onclick="countdown('countdown1');this.disabled = true;" value="Start" />
    <div id="countdown1"></div>
    
    <input type="button" onclick="countdown('countdown2');this.disabled = true;" value="Start" />
    <div id="countdown2"></div>
</body>

JavaScript

var interval;

var countdown1 = {
    minutes:0,
    seconds: 10
};

var countdown2 = {
    minutes:0,
    seconds: 2
}

    function countdown(element) {
        alert(element);
        var cd;
        element === 'countdown1' ? cd = countdown1 : cd = countdown2;
        interval = setInterval(function(timer) {
            var el = document.getElementById(element);
            if(cd.seconds == 0) {
                if(cd.minutes == 0) {
                    (el.innerHTML = "STOP!");     

                    clearInterval(interval);
                    return;
                } else {
                    cd.minutes--;
                    cd.seconds = 60;
                }
            }
            if(cd.minutes > 0) {
                var minute_text = cd.minutes + (cd.minutes > 1 ? ' minutes' : ' minute');
            } else {
                var minute_text = '';
            }
            var second_text = seconds > 1 ? '' : '';
            el.innerHTML = minute_text + ' ' + cd.seconds + ' ' + second_text + '';
            cd.seconds--;
        }, 1000);
    }
var start = document.getElementById('start');