JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1" style="width:20px; height:20px; background-color: yellow;"></div>

<div id="div2" style="width:20px; height:20px; background-color: blue;"></div>

<div id="div3" style="width:20px; height:20px; background-color: green;"></div>

<div id="div4" style="width:20px; height:20px; background-color: red;"></div>

JavaScript

var arr = new Array();

arr.push(document.getElementById("div1"));
arr.push(document.getElementById("div2"));
arr.push(document.getElementById("div3"));
arr.push(document.getElementById("div4"));

for(var i = 0; i < arr.length; i++)
    arr[i].onclick = function(){
                            alert(i);
                            return false;
                        };