Full page CSS spinner useful for pages with AJAX

ajaxFullPageSpinner.html

<div class="loading hidden"><i class="fa fa-spin fa-circle-o-notch" style="font-size: 48px;"></i></div>

<script type="text/javascript">
const formData = new FormData();
formData.append('key', 'value');
  
$.ajax({
  async: true,
  contentType: false,
  processData: false,
  url: '/some-endpoint',
  method: 'POST',
  data: formData,
  beforeSend: function(jqXHR, settings) {
    $('div.loading').removeClass('hidden');
  },
  error: function(jqXHR, textStatus, errorThrown) {
    // Handle error
  },
  success: function(data, textStatus, jqXHR) {
    // Process data
  },
  complete: function() {
    $('div.loading').addClass('hidden');
  }
});
</script>

<style>
    /* Absolute Center Spinner */
    .loading {
    position: fixed;
    z-index: 999;
    height: 2em;
    width: 2em;
    overflow: visible;
    margin: auto;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    }

    /* Transparent Overlay */
    .loading:before {
    content: '';
    display: block;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.3);
    }

     /* Animation */

    @-webkit-keyframes spinner {
    0% {
        -webkit-transform: rotate(0deg);
        -moz-transform: rotate(0deg);
        -ms-transform: rotate(0deg);
        -o-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    100% {
        -webkit-transform: rotate(360deg);
        -moz-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        -o-transform: rotate(360deg);
        transform: rotate(360deg);
    }
    }
    @-moz-keyframes spinner {
    0% {
        -webkit-transform: rotate(0deg);
        -moz-transform: rotate(0deg);
        -ms-transform: rotate(0deg);
        -o-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    100% {
        -webkit-transform: rotate(360deg);
        -moz-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        -o-transform: rotate(360deg);
        transform: rotate(360deg);
    }
    }
    @-o-keyframes spinner {
    0% {
        -webkit-transform: rotate(0deg);
        -moz-transform: rotate(0deg);
        -ms-transform: rotate(0deg);
        -o-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    100% {
        -webkit-transform: rotate(360deg);
        -moz-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        -o-transform: rotate(360deg);
        transform: rotate(360deg);
    }
    }
    @keyframes spinner {
    0% {
        -webkit-transform: rotate(0deg);
        -moz-transform: rotate(0deg);
        -ms-transform: rotate(0deg);
        -o-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    100% {
        -webkit-transform: rotate(360deg);
        -moz-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        -o-transform: rotate(360deg);
        transform: rotate(360deg);
    }
  }
</style>