JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" data-ajax="/echo/json/test" />

CSS

input {
    box-sizing: border-box;
    border: 1px solid #ccc;
    height: 30px;
    padding: 10px;
}
input.loading {
    background: url(http://www.xiconeditor.com/image/icons/loading.gif) no-repeat right center;
}

JavaScript

$(document).on('blur', 'input', function(e) {
    var $t = $(e.currentTarget);
    $t.addClass('loading');
    $.ajax({
        url: $t.data('ajax'),
        success: function(data) {
            //dostuff
            $t.removeClass('loading');
        }
    });
});