JSFiddle - React, Tailwind, and code Playground

HTML

<div id="contenedor">
  <div class="x" title="caja_1"></div>
  <div class="x" title="caja_2"></div>
  <div class="x" title="caja_3"></div>
</div>

CSS

div.x{
background: blue;
height: 50px;
width: 250px;
margin: 20px;
}

JavaScript

var div = document.getElementById("contenedor");
 
div.addEventListener("click",function(e){
var n = e.target.title;
return (n)? alert(n) : null;
},false);