The modal type cannot be automatically detected but must always be set explicitly. There exist 3 subtypes that cover the functionality of the 3 native javascript functions: alert, confirm and prompt. They are recognized by the attribute that sets their message:

<button type="button" class="bblb" data-bblb-force="modal" data-bblb-alert="Alert Text">Alert</button>
or
<button type="button" class="bblb" data-bblb-force="modal" data-bblb-confirm="Confirm Text">Confirm</button>
or
<button type="button" class="bblb" data-bblb-force="modal" data-bblb-prompt="Prompt Text">Prompt</button>

Compared to the native functions the modal type has the advantage that it can be styled and that the javascript execution will not stop until the window closes.

The modals will return the same value as their native counterparts (alert: undefined, confirm: true/false, prompt: user-input/null), but with some extra information to know the origin of the returned data. The data will be given to a callback-function.

$('.bblb').bbLightbox({
	onmodal: function(lb, data) { console.log(data); }
});

The data-object that gets passed to the callback-function is an object, with the following attributes:

{
	kind: 'alert/confirm/prompt',
	message: 'message that was shown to the user',
	val: returnValue
}

Modals will be opened without the closing- and the fullscreen-button and will not close when the background is clicked. This behavior can be configured.