Question

In Internet Explorer 7 some properties (mouse coordinates) are treated as physical while others are logical (offset). This essentially required Web developers to be aware of or calculate the zoom state. In IE8 release all properties are logical.

Answer 1

You can get it using:

var b = document.body.getBoundingClientRect();    
alert((b.right - b.left)/document.body.clientWidth);

Thanks a lot @niclasnorgren!