JSFiddle - React, Tailwind, and code Playground

HTML

<button type="" class="btn">Show Data</button>
<div id="loading" style="display:none;">Loading...</div>

JavaScript

$('.btn').on( "click" , function( event ){
   $.post( "/echo/json" , { "json" : JSON.stringify({"test":"test"}) } );
   return false;
});  
    
$(document).ajaxStart(function() {
    console.log("START");
    $("#loading").show();
}).ajaxStop(function() {
    console.log("END");
    $("#loading").hide('slow');
});