Update - If you're using Firefox, instead of using this userscript, I recommend setting privacy.resistFingerprinting and privacy.resistFingerprinting.letterboxing to true.
This works way better than spoofing these screen values.
This userscript alters the innerWidth and innerHeight, as well as the window.screen width and height properties to prevent attempts at fingerprinting your screen's resolution. The screen resolution is spoofed to 1920x1080, which is one of the most common screen resolutions out there.
Note: The innerHeight uses 974, which is Windows 7's taskbar height (1080 - 106px).
If you want to switch to Windows 10's taskbar height, edit the script and switch 974 to 966 (1080 - 114px).
Note 2: The outerHeight uses 1040, which is the screen resolution - 40px.
Note 3: Both the innerHeight and outerHeight use Chrome's resolutions as a baseline since Firefox is more variable and Chrome is more standardized and in use.
Install this userscript and then check some sites that calculate your screen resolution like:
www.screenresolution.orgwww.whatismyscreenresolution.comdev.jeffersonscher.com/resolution.htmlresizemybrowser.com
Screen resolution should show 1920x1080.
Only tested in Greasemonkey (pre-Firefox 57 version) and Firefox.
Probably does not work with Chrome or Firefox WebExtension alternatives like Tampermonkey and Violentmonkey. I'll be releasing a WebExtension version for Chrome and Firefox 57+ in the near future.
