JSFiddle - React, Tailwind, and code Playground

HTML

<div id="banner-message">
  <p>Lanzar eventod</p>
  <button>Lanzar</button>
  <div id="consola"></div>
</div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#banner-message {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  font-size: 25px;
  text-align: center;
  transition: all 0.2s;
  margin: 0 auto;
  width: 300px;
}

button {
  background: #0084ff;
  border: none;
  border-radius: 5px;
  padding: 8px 14px;
  font-size: 15px;
  color: #fff;
}

#banner-message.alt {
  background: #0084ff;
  color: #fff;
  margin-top: 40px;
  width: 200px;
}

#banner-message.alt button {
  background: #fff;
  color: #000;
}

JavaScript

// find elements
var banner = $("#banner-message")
var button = $("button")

// handle click and add class
button.on("click", function(){
 guardarx();
})
//esta funcion iria en otro fichero
function guardarx(){
//guardo con ajax...

// Creo el evento
var event = new CustomEvent("evento-guardar-x", { "Parametro": "Valor" });
//Lanzo el evento
document.dispatchEvent(event);
}

document.addEventListener("evento-guardar-x", function(e) {
$('#consola').html("Se ha capturado");
});