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

On Chrome

var ratio = (screen.availWidth / document.documentElement.clientWidth);
var zoomLevel = Number(ratio.toFixed(1).replace(".", "") + "0");