if(window.addEventListener){ 
alert("not ie"); 
}else if(window.attachEvent){ 
alert("is ie"); 
}else{ 
alert("这种情况发生在不支持DHTML的老版本浏览器（现在一般都支持）") 
}

if(document.all){ 
alert("IE"); 
}else{ 
alert("not ie"); 
}

var navigatorName = "Microsoft Internet Explorer"; 
if( navigator.appName == navigatorName ){ 
alert("ie") 
}else{
alert("not ie") 
}

if(!+[1,])alert("这是ie浏览器"); 
else alert("这不是ie浏览器");

var explorer =navigator.userAgent ;
//ie 
if (explorer.indexOf("MSIE") >= 0) {
alert("ie");
}
//firefox 
else if (explorer.indexOf("Firefox") >= 0) {
alert("Firefox");
}
//Chrome
else if(explorer.indexOf("Chrome") >= 0){
alert("Chrome");
}
//Opera
else if(explorer.indexOf("Opera") >= 0){
alert("Opera");
}
//Safari
else if(explorer.indexOf("Safari") >= 0){
alert("Safari");
} 
//Netscape
else if(explorer.indexOf("Netscape")>= 0) { 
alert('Netscape'); 
} 

$(document).ready(function(){

  var brow=$.browser;

  var bInfo="";

  if(brow.msie){bInfo="MicrosoftInternetExplorer"+brow.version;}

  if(brow.mozilla){bInfo="MozillaFirefox"+brow.version;}

  if(brow.safari){bInfo="AppleSafari"+brow.version;}

  if(brow.opera){bInfo="Opera"+brow.version;}

  alert(bInfo);

});