JSFiddle - React, Tailwind, and code Playground

HTML

<div class="answer1wrap">
  <label>Select your top champion: </label>
	<select id="topSelect">
	<option value="void">Select a champion</option>
	<option value="aatrox">Aatrox</option>
	<option value="ahri">Ahri</option>
	<option value="akali">Akali</option>
	</select>
</div>

<button class="btn btn-default" id="checkbtn"  type="button"><span    class="glyphicon glyphicon-check"></span> Calculate Win Chance</button>

<div class="display">
    <p>The top champion you selected is: </p>
</div>

JavaScript

function topAnswer(){
	var element = document.getElementById("topSelect");
	var elementValue = element.value;
	if(elementValue == "aatrox"){
	
	var div = document.getElementsByClassName('display')[0];
	var ptag = div.getElementsByTagName('p')[0];
		if(typeof greeting == 'undefined'){
			greeting = ptag.innerHTML;
		}
		ptag.innerHTML = greeting + elementValue;
		
	}
}

document.getElementById('checkbtn').addEventListener('click', topAnswer);