Strict liability for the owner, with three elements
N.J.S.A. 4:19-16, as explained in New Jersey's model civil jury charge, makes the owner of any dog that bites a person in a public place, or lawfully in a private place including the owner's property, liable for the damages suffered regardless of the dog's former viciousness or the owner's knowledge of it. The injured person must show that the defendant owned the dog, that the dog bit them, and that the bite occurred in a public place or while they were lawfully on private property.
Provocation and trespass are the usual defenses, and the Comparative Negligence Act applies to reduce an award for the victim's own fault.