code: function( t ) {
  
  		var delta = 0.0001;
  		var t1 = t - delta;
  		var t2 = t + delta;
  
  		// Capping in case of danger
  
  		if ( t1 < 0 ) t1 = 0;
  		if ( t2 > 1 ) t2 = 1;
  
  		var pt1 = this.getPoint( t1 );
  		var pt2 = this.getPoint( t2 );
  
  		var vec = pt2.clone().sub( pt1 );
  		return vec.normalize();
  
  	}
docs: Returns a unit vector tangent at t In case any sub curve does not implement its tangent derivation, 2 points a small delta apart will be used to find its gradient which seems to give a reasonable approximation