Its okay if they date as long he don't treat her wrong... just get here pregnancy pills or the pregnancy shot so she won't get pregnant really young...

It is OK to date ( not to have sex) as long as it is OK with you.
If you don't want them dating, you can just tell them no

There do not appear to be any laws regarding 'dating'. The age of consent is 16. However, 13-15 year olds can consent to sex with people no more than four years older than they are. This article is the best explanation I have found so far:
New Jersey Age of Consent Laws - Labor Law Talk Blog

Since, this is being asked in Dating instead of on one of the Legal boards, I will add that you are her parent and as such have control over when she dates. If you don't want her to, don't allow it.

While they may be of legal age, I highly hope you have had the "talk" with your daughter, and explained in great details the facts of life to her. If not, then you are sending her into a very dangerous world with no tools to defend herself with.

Its up to you as a mom, to protect her, by knowing where she is, at all times, and who she is dating very well. While it may be legal for her to date, its still your responsibility to make rules and boundaries she has to abide by.