code: function(a,b) {
  			var v = _getXY(a,b);
  			this.x += mathUtils.normalizedRandom() * v.x;
  			this.y += mathUtils.normalizedRandom() * v.y;
  			return this;
  		}
docs: Adds random jitter to the vector in the range -j ... +j using the default
  {@link Random} generator of {@link MathUtils}.
  
  @param a
  maximum x jitter or  Vec2D
  @param b
  maximum y jitter or undefined
  @return itself