JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="foo">
    <li>111</li>
    <li>222</li>
    <li>333</li>
</ul>

JavaScript

window.onload = function() {
    var ul = document.getElementById("foo");
    var lis = ul.getElementsByTagName("li");
    for(var i=0; i<lis.length; i++) {
        lis[i].onmouseover = function(x) {
            return function() {
                console.log(x);
            }
        }(i);
    }
};