How Confirm before delete?

[eluser]augustowloch[/eluser]
agree with Michael Wales,

It's also useful sometimes to show something else than just a confirm popup.
When i'm deleting a record, I like to show a complete detail of the record to be deleted, so the user can be sure what's deleting. btw, sometimes I also make some validations and show extra-warnings in this confirmation form, before real deletion.

So, in conclusion, if the nature of the data being deleted doesn't deserves more atention than a simple pop-up warning, just use a JS, or nothing at all, but if you are developing an ERP and want to confirm before deleting an invoice, well.. I recomend to show a form detailing the invoice, and spend 1 extra trip(POST) to the server. (it could be showed via ajax to make it look nice, but it keeps being an extra trip to the server )