JSFiddle - React, Tailwind, and code Playground

HTML

<div id="foo">add ID</div>

CSS

#new{
    height:250px;
    width:250px;
    background:#eee;
    margin:25px;
}

JavaScript

var a=$('div').attr('id');
console.log(a);
$('div').attr('id', 'new '+a);