gistfile1.js

dojo.addOnLoad(function(){
	dijit.registry.byClass("dijit.form.DateTextBox").forEach(function(w){
		if(w.class == 'hugDatePicker'){

			w.validator = function(value, constraints){

				var deferred = isValidDate(value);
				
				return deferred.then(function(value){
					console.log(value);
					if(value.indexOf("OK") != -1){
						return true;
					}else{
						w.displayMessage(value);
						return false;
					}
				},
				function(error){
					console.log(error);
					return false;
				});

				
			}
		}
	});
});


function isValidDate(date){
	var xhrArgs = {
		url: site_url + '/hugs/validateDeliveryDate',
		content: {
			"date":date,
			"csrf_bear_hugs": csrf_hash,
		},
		timeout: 2000,
		load: function(data) {
			return data;
		},
		error: function(error) {
			console.log(error);
		}
	}
	var deferred = dojo.xhrPost(xhrArgs);

	//console.log(deferred);

	return deferred;
}