Read about this, seems to be a good alternative to the spray and is legal in NJ. I like that it has a 5 round capacity and long range with a laser sight. Also a flashlight and it doesn't look like a weapon. And you do not have to hit the target, be it coyotes, dogs or whatever, for it to be effective. A smaller version would be nice. A bit on the pricey side, but...
Have you read the knife regulations? 