JSFiddle - React, Tailwind, and code Playground

HTML

<button id="add">Ajouter</button>
<br />
<div id="content"></div>

JavaScript

var inputId = 0;
$("#add").click(function() {
    var newNode = '<div id="subcontent'+(++inputId)+'">'; // incrémente l'id avant de l'utiliser
    newNode += '<input type="text" placeholder="Champ '+inputId+'" id="input'+inputId+'" />';
    newNode += '</div>';
    $("#content").append(newNode);
});