Event.observe(window, 'load', function(event) {
    Event.observe($('username'), 'change', function () { checkAvailability('username'); }); 
    Event.observe($('email'), 'change', function () { checkAvailability('email'); }); 
});


/*
*
*/
function checkAvailability(field) {
    
    new Ajax.Updater(
        field + 'Availabity',
        baseURL() + 'user/' + field + 'Availability',
        {
            method: 'post',
            parameters: field + '=' + escape($(field).value) + '&ajax=1' + noCacheParam()
        }
    );
}