mask-border-repeat: value;
object.style.maskBorderRepeat = "value";
<'mask-border-repeat'> = [ stretch | repeat | round | space ]{1,2}
stretch
The image is stretched to fill the area.
repeat
The image is repeated in the horizontal and vertical direction as often as needed to cover the area.
round
The image is repeated as often as will fit within the area. If it doesn't fit a whole number of times, it is rescaled so that it does.
space
The image is repeated as often as will fit within the area without being clipped and then the images are spaced out to fill the area.