JSFiddle - React, Tailwind, and code Playground

HTML

<div class="f">percentage</div>

CSS

.f
{
    width:73%;
    background-color:red;
    position:relative;
    margin:0 auto;
}

JavaScript

$(document).ready(function(){
    var percent =  $('.f').width() / $('body').width() * 100;
    console.log(Math.round(percent));       
});