JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1" class="my-element" style="width:100%"></div>
<div id="div2" style="width:100%"></div>

CSS

.my-element {
    width:100%;
}

JavaScript

alert("Width of div1 with css = "+ $('.my-element').css('width'));
div2 = document.getElementById('div2');
alert("Width of div2 with style = " + div2.style.width);