Form Element AJAX Spinner Attachment Using MooTools

Many times you'll see a form dynamically change available values based on the value of a form field. For example, a "State" field will change based on which Country a user selects. What annoys me about these forms is that they'll often do an AJAX request to grab the states but wont show any indicator to the user that something is happening. We're going to use MooTools to add an AJAX spinner image next to form fields that perform such AJAX requests.

The XHTML

<select class="ajax">
	<option value="">-- Select a Site--</option>
	<option value="David Walsh Blog">David Walsh Blog</option>
	<option value="Script & Style">Script & Style</option>
	<option value="Band Website Template">Band Website Template</option>
</select>

<br /><br />

<input type="text" id="my-text" class="ajax" />

Add the "ajax" class (or any class for that matter) to the elements you'd like the spinner to display by.

The MooTools JavaScript

window.addEvent('domready',function() {
	//inject image
	var spinner = new Element('img',{
		src: 'move-spinner.gif',
		styles: {
			position:'absolute'
		},
		opacity: 0
	}).inject(document.body);
	//form element events
	$$('.ajax').each(function(el) {
		//get coordinates
		var coords = el.getCoordinates(document.body);
		//ajax request object
		var request = new Request({
			url: '',
			method: 'post',
			onRequest: function() {
				spinner.setStyles({
					left: coords.right + 10,
					top: coords.top + 5
				}).fade('in');
			},
			onComplete: function() {
				spinner.fade('out');
			}
		});
		//change event
		el.addEvent('change',function() {
			//ajax request
			request.send({
				data: {
					ajax: 1,
					value: el.get('value')
				}
			});
		});
	});
});

We first add the spinner image to the document but hide it right away. When any of the form elements with the "ajax" class changes value, we move the spinner image to the right of the element. Then we use Reqeust's onRequest and onComplete methods to show and hide the spinner. Simple!

Look forward to a jQuery version tomorrow.