Gets the X coordinate of the top-left corner of the window's viewport, in screen coordinates.

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 the nsIDOMWindowUtils.screenPixelsPerCSSPixel property.


screenX = window.mozInnerScreenX;


  • screenX stores the window.mozInnerScreenX property value.
  • The window.mozInnerScreenX property is a floating point, read-only value; it has no default value.


Not part of any W3C technical specification or recommendation.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support No No Yes No No No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No No No Yes No No No

See also

Document Tags and Contributors

Contributors to this page: connorshea, sarafec, fscholz, teoli, libreGeekingKid, Sheppy, ethertank
Last updated by: connorshea,