JavaScript检测浏览器类型与IE版本的多种实现方案

 
var isIE=!!window.ActiveXObject;
var isIE6=isIE&&!window.XMLHttpRequest;
var isIE8=isIE&&!!document.documentMode;
var isIE7=isIE&&!isIE6&&!isIE8;
if (isIE){
if (isIE6){
alert("ie6");
}else if (isIE8){
alert("ie8");
}else if (isIE7){
alert("ie7");
} 
} 

 
if(navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/6./i)=="6."){
alert("IE 6");
} 
}else if(navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/7./i)=="7."){
alert("IE 7");
} 
}else if(navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/8./i)=="8."){
alert("IE 8");
} 
}else if(navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/9./i)=="9."){
alert("IE 9");
} 

 
if(navigator.userAgent.indexOf("Opera") != -1) {
alert('Opera');
} 
}else if(navigator.userAgent.indexOf("MSIE") != -1) {
alert('Internet Explorer');
} 
}else if(navigator.userAgent.indexOf("Firefox") != -1) {
alert('Firefox');
} 
}else if(navigator.userAgent.indexOf("Netscape") != -1) {
alert('Netscape');
} 
}else if(navigator.userAgent.indexOf("Safari") != -1) {
alert('Safari');
} 
}else{
alert('无法识别的浏览器。');
} 

 
if(!+'\v1' && !'1'[0]){
alert("ie6或ie7")
}