King's sixth goal of the season came at 13:08. Defenseman Jake Muzzin's drive from the left point was redirected by King, standing in front of goalie Cory Schneider.
Kopitar scored an empty-net goal with 2.9 seconds left. Schneider made 19 saves.
Friday's game was the Kings' first visit to the Prudential Center since playing the Devils in the 2012 Stanley Cup finals.
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