Referring to my earlier post jQuery: Show Loading…, a better way to show & hide loading icon – by binding to ajaxSend and ajaxComplete event.

The Html Markup

 <div id="loading" class="overlay-loading">
    <i class="loading-icon fa fa-5x fa-circle-o-notch fa-spin"></i>
 </div>

The CSS

.overlay-loading {
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    right: 0;
    background: #000;
    opacity: 0.8;
    filter: alpha(opacity=80);
    z-index: 2000;
}
.loading-icon {
    position: absolute;
    top: 50%;
    left: 50%;
}

The JavaScript

$(document).bind("ajaxSend", function(){
   $("#loading").show();
 }).bind("ajaxComplete", function(){
   $("#loading").hide();
 });

References:

1. Ajax Events
2. JsFiddle
3. FontAwesome