JSFiddle - React, Tailwind, and code Playground

HTML

<form id="myform" action="javascript:alert('envoyé')" onsubmit="alert(this.id)" >
    <fieldset id="fs">
        <legend>famille</legend>
        <input type="text" id="bar" value="coucou" />
    </fieldset>
    <input type="submit" id="valid" value="valid" />
</form>
<input type="button" id="clone" value="clone" />
<div id="output"></div>

JavaScript

var inc=0;
$("#clone").click( function(){
  $newfs = $('#fs').clone(true).attr("id","fs"+ ++inc);
      $('#newfs :text').attr('id',"bar"+inc);
  $("#valid").before( $newfs );
    
      })