How to detect page zoom level in all modern browsers?

Question

1. How can I detect the page zoom level in all modern browsers? While this thread tells how to do it in IE7 and IE8, I can\'t find a good cross-browser solution.

Answer 1

here it does not change!:

 
  
 

 

  foobar
 
 

  Show
 

create a simple html file, click on the button. regardless of what zoom level: it will show you the width of 400px (at least with firefox and ie8)