JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test1">Test</div>

JavaScript

var NewElement=$("#test1").clone();
var IDNr=NewElement.attr("id").match(/\d+$/);

NewElement.attr("id",NewElement.attr("id").replace(IDNr,parseInt(IDNr)+1));
        
alert(NewElement.attr("id"));