JSFiddle - React, Tailwind, and code Playground

HTML

<form action="<?php $_SERVER['REQUEST_URI']; ?>" method="post" id="registrationForm" class="formulaire">
                        <div class="input-group">
                        <div class="col-6">
 
 
 
 
                                <label class="" for="numero_piece">
                                    <h4>Numéro de pièce</h4></label>
                                <input type="text" class="numero_piece" name="numero_piece" id="numero_piece"  title="enter your first name if any." >
 
 
                        </div>
                        <div class="col-6">
 
 
                                <label for="intitule_piece">
                                    <h4>Intitulé</h4></label>
                                <input type="text" class="intitule_piece" name="intitule_piece" id="intitule_piece" placeholder="last name" title="enter your last name if any." >
 
                        </div>
                    </div>
 
                    <button  type="submit" name="valider"><i class=" submit "></i> Valider</button>
                </form>

JavaScript

$(document).ready(function(){
	$('.formulaire').submit(function(e){
  e.preventDefault();
		var num = $('.numero_piece').val();
		var intitule = $('.intitule_piece').val();
 
		alert (num + intitule);
    });
 
 
	});