====== utilisation d'une REF ======


  handlesubmit = (event) => {
    event.preventDefault();
    console.log(this.clientimput.current.value);};
    
 
    
  <form onSubmit={this.handlesubmit}>
     <input ref={this.clientimput} type="text" placeholder="ajouyer un souhait" />
     <button>Validation</button>
   </form>


====== utilisation d'une state ======

  state = {
    clients: [
      { id: 1, nom: "toto" },
      { id: 2, nom: "tutu" },
      { id: 3, nom: "titi" }
    ],
    nouvveauclient: "";
  };