PolarChart.setGridStyle

Configure whether to use circular grids or polygon grids, and whether the grid lines are on top of the polar plot area or are at the back.

Argument	Default	Description
polygonGrid	(Mandatory)	A true (non-zero) value means polygonal grid will be used. A false (zero) value means circular grid will be used.
gridOnTop	true (non-zero)	A true (non-zero) value means the grid lines will be on top of the polar plot area. A false (zero) value means the grid lines will be at the bottom of the polar plot area.