DataJS: Storing OData.read() result in local and global variable is undefined

Question

I'm trying to pass my OData.read result into a global and a local variable, but eventually, each of them is undefined.

var foo_global;

function doIt()
{
    var foo_local;

    $.ajaxSetup
    ({
        cache:false
    });

    OData.defaultHttpClient.enableJsonpCallback = false;

    OData.read(url,
        function (data)
        {
            foo_local = data;
            foo_global = data;
            alert(data); // works!
        },
        function (err)
        {
            alert('error');
        }
    );

    alert(foo_local); // undefined
    alert(foo_global); // also undefined
}