JSFiddle - React, Tailwind, and code Playground

HTML

<div><input id="field1" type="text" maxlength="1" size="5" /></div><div><label id="label1">Not yet pressed</label></div>

JavaScript

var start = function(){

	var fieldElement = document.getElementById('field1');
	fieldElement.addEventListener('keyup',functionOnKeyUp,false);
	fieldElement.addEventListener('keydown',functionOnKeyDown,false);
};
document.addEventListener('DOMContentLoaded', start, false);

var limitOnKeyDown = 0;

function functionOnKeyUp(){
	limitOnKeyDown = 0;
	document.getElementById('label1').innerHTML  = "Key Up";
}

function functionOnKeyDown(){
    //invokaš funkcijo samo prvič
	if(limitOnKeyDown === 0){
		document.getElementById('label1').innerHTML  = "";
		document.getElementById('label1').innerHTML  += "Key Down";
        limitOnKeyDown++;
    }
}