N.J. Stat. § 39:4-126
No person shall turn a vehicle at an intersection unless the vehicle is in proper position upon the roadway as required in section 39:4-123, or turn a vehicle to enter a private road or driveway or otherwise turn a vehicle from a direct course or move right or left upon a roadway, or start or back a vehicle unless and until such movement can be made with safety. No person shall so turn any vehicle without giving an appropriate signal in the manner hereinafter provided in the event any other traffic may be affected by such movement.
A signal of intention to turn right or left when required shall be given continuously during not less than the last 100 feet traveled by the vehicle before turning.
No person shall stop or suddenly decrease the speed of a vehicle without first giving an appropriate signal in the manner provided herein to the driver of any vehicle immediately to the rear.
The signal herein required shall be given either by means of the hand and arm in the manner herein specified, or by an approved mechanical or electrical signal device, except that when a vehicle is so constructed or loaded as to prevent the hand and arm signal from being visible, both to front and rear, the signal shall be given by a device of a type which has been approved by the division.
When the signal is given by means of the hand and arm, the driver shall indicate his intention to stop or turn by extending the hand and arm from and beyond the left side of the vehicle in the following manner and such signals shall indicate as follows:
N.J.S. § 39:4-126