JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" id="button" value="send" />

JavaScript

$('#button').click(function() {
    $.when(
        $.ajax({
            url: '/echo/html/',
            success: function(data) {
                alert('request complete')
            }
        }),
        $.ajax({
            url: '/echo/html/',
            success: function(data) {
                alert('request complete')
            }
        })
    ).then( function(){
        alert('all complete');
    });
});