JSFiddle - React, Tailwind, and code Playground

HTML

<form id="myform" action="http://cnn.com/" enctype="multipart/form-data" method="post">
  <input type="button" id="loginbtn" value="Login" />
</form>

JavaScript

$(document).ready(function(){
  $("#loginbtn").click(function(){  /* When login is clicked */
    $("body").fadeOut(3000,function(){  /* Three second fade out */
      $("#myform").submit();  /* Submit the form after the fade out is done */
    });
  });
});