Client has a multi-step process (wizard, if you will) for enrollment in their program. Client wants a confirmation to be presented to users who abandon the enrollment mid-way (such as clicking navigation, new URL).

I presented a non-modal re-display of the current page with the addition of a confirmation box + yes/no buttons that adhered to the look/feel of the rest of their site. This was approved and all was well.

Client now wants the confirmation modal, forcing the user to click one way or the other. Clearly javascript confirmation comes to mind (modal OK and CANCEL). Code to achieve this is easy.

I can live with the fact that the vanilla js confirmation doesnt adhere to the sites overall design look/feel. Moreover, I personally dont see js confirm used any longer for modal prompts. if seen, its a lightbox approach, not js confirm.

QUESTIONS / REQUEST FEEDBACK
Will js confirmation's ever by blocked by user-agent blockers?
Are there discussion-threads for/against their use?
Are you using them on your recent websites?
If presented with same toss-up, would you go js confirm route or some other modal method (lightbox)?

http://www.candsdesign.co.uk/article...-a-disclaimer/

Sort-of "lightbox" style.

user agents and pop-up blockers should never, ever block alert confirmations/warnings

javascript confirm function would the best way in terms of usability.

unless you're prepared for compatibility issues, go for lightboxes.

good luck!