I'm trying to get the width of my screen in pixels using JavaScript.

e.g. window.width, window.outerWidth, screen.width, screen.availWidth, etc.

The highest value I get back is 1280. However, my screen resolution is set at 1920 x 1080. So why doesn't JavaScript display 1920.

I'm using a Microsoft Surface Pro, Windows 8 and Internet Explorer 10.