JSFiddle - React, Tailwind, and code Playground

HTML

<button id="js-in-id">
+10 min
</button>
<input type="text" readonly value="1:00" data-minutes="60" id="js-input-id" />
<button id="js-de-id">
-10 min
</button>

JavaScript

var formatTime = function(minutes){
	var date = new Date(minutes * 60000),
		hh = date.getUTCHours(),
		mm = date.getUTCMinutes();

	if(hh < 10){
		hh = "0" + hh;
	}

	if(mm < 10){
		mm = "0" + mm;
	}

	return hh + ":" + mm;
};

var inBtn = document.getElementById('js-in-id'),
	deBtn = document.getElementById('js-de-id'),
	input = document.getElementById('js-input-id');

inBtn.addEventListener('click', function(){
	var minutes = parseInt(input.dataset.minutes);
	minutes += 10;
	input.value = formatTime(minutes);
	input.dataset.minutes = minutes;
});

deBtn.addEventListener('click', function(){
	var minutes = parseInt(input.dataset.minutes);
	if(minutes > 10){
		minutes -= 10;
		input.value = formatTime(minutes);
		input.dataset.minutes = minutes;
	}
});