JSFiddle - React, Tailwind, and code Playground

HTML

<div class="border">
        <div id="box1" style="width:100px; height:100px; background-color: #000000;">
        </div>

    </div>

JavaScript

var colorcheck = "#cccccc";

 function click1(blockid) {
   alert("calling");   
   document.getElementById("box" + blockid).style.backgroundColor = '#ff0000';
   colorcheck = document.getElementById("box1").style.backgroundColor;
   console.log(colorcheck);
   console.log("box" + blockid);
 };
 document.getElementById("box1").addEventListener("click", function(){click1(1);}, false);