The Screen Object

The Screen object has been supported since Internet Explorer 4.0 and Netscape 3.0 back in 1996. It can be used to determine details about the users screen size and colour depths etc. This can prove useful if content positioning relies on the size of the users screen.

Properties of window.screen.
availHeight
The availHeight property returns a value representing the available height of the users screen. This is the height property, minus that taken by any toolbars (i.e. the taskbar)

availWidth
The availWidth property returns a value representing the available width of the users screen. This is the width property, minus that taken by any toolbars (e.g. the Office toolbar)

availTop, availLeft
The top and left edge of the current screen area. Nonstandard, use

bufferDepth IE ONLY!
The bufferDepth property can be used to set an off screen buffering value. Setting the bufferDepth to "0", no explicit buffering is set and the colorDepth property is set to the screen depth. If bufferDepth is set to "-1" (the default), then off screen buffering is performed at the current screen depth and the colorDepth property matches the screen depth.

The bufferDepth property can be set to 1, 4, 8, 15, 16, 24 or 32, which then causes off screen buffering to occur at the set bit-per-pixel depth. i.e. bufferDepth=8 performs buffering at 8 bits per pixel, which is 256 colours. Setting the bufferDepth to any other value causes it to be set to "-1".

Note that when bufferDepth is "-1", if the user changes their system settings, the bufferDepth is automatically changed to the new screen depth.

colorDepth
The colorDepth property is read-only and reflects the users current system color depth settings, in bits-per-pixel. I.e. 256 colours, colorDepth=8, 16.7million colours, colorDepth=16.

Note that the colorDepth property is dependent on the bufferDepth property. If bufferDepth is set to 0 or -1, then colorDepth is equal to the bits-per-pixel value of the users system settings. However, if the bufferDepth has been explicitly set to a different value, then the colorDepth property is equal to the bufferDepth property.

fontSmoothingEnabled IE ONLY!
The fontSmoothingEnabled property returns a boolean value indicating whether the user has font smoothing enabled on their system or not.

height
The height property reflects the users current screen height, in pixels.

updateInterval IE ONLY!
The updateInterval property can be used to set (in mSec), the time between updates for the current viewing window. This is only really a problem when large (size or amount) moving, or continually refreshing images are present in a page.

setting updateInterval=0 resets the screen update Interval to its default setting, chosen by Internet Explorer.

width
The width property reflects the users current screen width, in pixels.

Methods
The Screen Object has no methods.

Events
The Screen Object has no events.

© 1995-1998, Stephen Le Hunte

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