Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

Note:This coordinate is reported in CSS pixels, not in hardware pixels. That means it can be affected by the zoom level; to compute the actual number of physical screen pixels, you should use thensIDOMWindowUtils.screenPixelsPerCSSPixel property.