JSFiddle - React, Tailwind, and code Playground

HTML

<div class="cont">
  Click Alt + Ctrl<br /><br />
  <div id="res"></div>
</div>

CSS

.cont{
  width: 110px;
  margin: 0 auto;
}

#res{
  border: 1px solid black;
  border-radius: 3px;
  background-color: #e5e5e5;
  width: 100px;
  height: 30px;
  font-size: 20px;
  margin: 0 auto;
  text-align: center;
  padding: 10px;
}

JavaScript

var lastAltLocation;

document.addEventListener("keydown", function(e) {
   if (e.key == "Alt"){
     lastAltLocation = e.location;
   }
   if (e.ctrlKey && e.altKey){
       if (lastAltLocation == 1){
           document.getElementById("res").innerHTML = "Left";
       }
       if (lastAltLocation == 2){
           document.getElementById("res").innerHTML = "Right";
       }
   }
  
}, false);