simple jQuery Deferred example

jquery.deferred.promise.js

function getData() {
    var deferred = $.Deferred();

    $.ajax({
        'url': 'http://google.com',
        'success': function(data) {
            deferred.resolve('yay');
        },
        'error': function(error) {
            deferred.reject('boo');
        }
    });

    return deferred.promise();
}

$.when(getData()).done(function(value) {
    alert(value);
});

getData().then(function(value) {
	alert(value);
});

Complete example!

function getData() {
    var deferred = $.Deferred();

    $.ajax({
        'url': 'http://google.com',
        'success': function(data) {
            deferred.resolve('yay');
        },
        'error': function(error) {
            deferred.reject('boo');
        }
    });

    return deferred.promise();
}

$.when(getData()).done(function(value) {
    alert(value);
});

getData().then(
function(value) {
	alert(value);
},
function (error) {
    alert(error);
});