gistfile1.txt

var ops = [], i, len;

for (i = 0, len = models.length; i < len; ++i) {
    ops.push(new Y.Promise(function (resolve, reject) {
        Y.io('save-my-stuff.php', {
            data: models[i].toJSON(),
            on: {
                success: function (id, xhr) {
                    // Maybe you want to JSON parse the responseText first?
                    // Maybe you don't care about the response beyond it being 200?
                    resolve(xhr.responseText);
                },
                failure: function () {
                    reject(new Error("IO error"));
                }
            }
        });
    });
}

Y.batch.apply(Y, ops).then(
    function () {
        console.log('All models saved');
    },
    function (reason) {
        console.log('Uh oh. Something went wrong: ' + reason);
    });