jQuery.when understanding

Solution 1:

function showData(data1, data2) {
    alert(data1[0].max_id);
    alert(data2[0].max_id);
}

function method1() {
    return $.ajax("http://search.twitter.com/search.json", {
        data: {
            q: 'ashishnjain'
        },
        dataType: 'jsonp'
    });
}

function method2() {
    return $.ajax("http://search.twitter.com/search.json", {
        data: {
            q: 'ashishnjain'
        },
        dataType: 'jsonp'
    });
}

$.when(method1(), method2()).then(showData);​

Here's a working jsFiddle

Solution 2:

The problem is that you're passing showData() to then(), not showData. You should pass a reference to a function to .then():

$.when(method1(), method2())
    .then(showData);

or

$.when(method1(), method2())
    .then(function () {
        showData();
    });

Edit

I've put together a working demo. Part of the problem (at least in the code fragment you posted) was that there was no callback function named $callback. Part of the problem was the $ in the callback name '$callback'.

So, remove the jsonp: '$callback' ajax option, so that jQuery defaults to a callback function named callback, and define a function with that name, and it all works.