Javascript browser detection using DOM capabilities

Just found this, pretty handy!

// browser detection

var isIE = document.all;
var isIE7 = isIE && window.XMLHttpRequest && window.ActiveXObject;
var isIE6 = isIE && document.implementation;
var isgteIE6 = isIE7 isIE6;
var isIE5 = isIE && window.print && !isgteIE6;
var isIEDOM2 = isIE5 isgteIE6;
var isIE4 = isIE && !isIEDOM2 && navigator.cookieEnabled;
var isIE3 = isIE && !isIE4 && !isIEDOM2;
var isNS = navigator.mimeTypes && !isIE;
var isNS3 = isNS && !navigator.language;
var isNS4 = document.layers;
var isNS6 = document.getElementById && !isIE;
var isNS7 = isNS6;
var isNS71 = document.designMode;
var isNSDOM2 = isNS6;
var isDOM2 = isIEDOM2 isNSDOM2;