Focus the first field in modal forms

I am using Bootstrap, from Twitter for genereting modal-dialog in a Marionette Application.

I would like to know what is the best way to focus the first field in modal forms without using fancy javascript.

Here my code:

var app = new Marionette.Application();

app.addRegions({
    modal: '#modal'
});

app.vent.on('showModal', function (view) {
    var modal = app.modal;

    modal.show(view);
    modal.$el.modal({
        show: true,
        keyboard: true,
        backdrop: 'static'
    });
});