JS代码判断IE6,IE7,IE8,IE9！

var browser=navigator.appName 
var b_version=navigator.appVersion 
var version=b_version.split(";"); 
var trim_Version=version[1].replace(/[ ]/g,""); 
if(browser=="Microsoft Internet Explorer" && trim_Version=="MSIE6.0") 
{ 
alert("IE 6.0"); 
} 
else if(browser=="Microsoft Internet Explorer" && trim_Version=="MSIE7.0") 
{ 
alert("IE 7.0"); 
} 
else if(browser=="Microsoft Internet Explorer" && trim_Version=="MSIE8.0") 
{ 
alert("IE 8.0"); 
} 
else if(browser=="Microsoft Internet Explorer" && trim_Version=="MSIE9.0") 
{ 
alert("IE 9.0"); 
} 


//判断是否低于ie9


function lowerIE9() {
    var browser = navigator.appName
    var b_version = navigator.appVersion
    var version = b_version.split(";");
    var trim_Version = version[1].replace(/[ ]/g, "");
    if (browser == "Microsoft Internet Explorer" && (trim_Version == "MSIE6.0" || "MSIE7.0" || "MSIE8.0")) {
      return true
    }
  }