JSFiddle - React, Tailwind, and code Playground

HTML

<p id="object1">O</p>
<p id="object2">O</p>
<p id="object3">O</p>

JavaScript

var nodeList = document.getElementsByTagName('p');

for(var i = 0; i < nodeList.length; i++)
{ 
    var obj = nodeList[i];
    obj.addEventListener('mouseover', function(e){
        e.target.innerHTML = '*';
    }, false);
}