JSFiddle - React, Tailwind, and code Playground

HTML

<div class="left"></div><div class="right"></div>
<a href="javascript:move()">MOVE</a>

CSS

div.left, div.right {
    width: 10px;
    height: 10px;
    float: left;
}

div.left {
    background-color: red;
}

div.right {
    background-color:green;
}

JavaScript

window.move = function() {
    var $left = $("div.left");
    var $right = $("div.right");
    for (var i =0; i<100; i++) {
        $left.css("width", i);
        console.log($right.position())
    }
}