// ---------------------------------------------------------- // A short snippet for detecting versions of IE in JavaScript // without resorting to user-agent sniffing // ---------------------------------------------------------- // If you're not in IE (or IE version is less than 5) then: //     ie === undefined // If you're in IE (>=5) then you can determine which version: //     ie === 7; // IE7 // Thus, to detect IE: //     if (ie) {} // And to detect the version: //     ie === 6 // IE6 //     ie > 7 // IE8, IE9 ... //     ie < 9 // Anything less than IE9 // ---------------------------------------------------------- // UPDATE: Now using Live NodeList idea from @jdalton var ie = (function(){     var undef,         v = 3,         div = document.createElement('div'),         all = div.getElementsByTagName('i');     while (         div.innerHTML = '<!--[if gt IE ' + (++v) + ']><i></i><![endif]-->',         all[0]     );     return v > 4 ? v : undef; }());

var a= 'b', c = 'd', e = 'f'； var obj = {  a: 'b',  c: 'd',  e: 'f' }

var a = (1,2,3,5,6,0,9,4); // a === 4