Overview
See MDN Screen InterfaceBasic Properties
orientation
Return the color/pixel Depth of the screen, as it's currently configured (e.g., in the Monitors control panel).
onorientationchange
Available Top/Left, Height/Width
These properties return the available space on the Screen that's not being used by the operating system. For example, OS X has a menu bar that uses some of the screen pixels at the top of the screen. A dock can be positioned on the left of the screen and will consume a variable amount of pixels, depending on its configured size.
Screen Top/Left, Height/Width
Return the total screen size in pixels, as it's currently configured (e.g., in the Monitors control panel).
Color/Pixel Depth
Return the color/pixel Depth of the screen, as it's currently configured (e.g., in the Monitors control panel).