JS代码判断IE6,IE7,IE8,IE9！做网页有时候会用到JS检测IE的版本，下面是检测Microsoft Internet Explorer版本的代码：
第一种方法：

<script type = "text/javascript">
  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"); 
  }
</script>

第二种：

<script type = "text/javascript">
if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.split(";")[1].replace(/[ ]/g, "") == "MSIE6.0") {
    alert("IE 6.0")
} else if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.split(";")[1].replace(/[ ]/g, "") == "MSIE7.0") {
    alert("IE 7.0")
} else if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.split(";")[1].replace(/[ ]/g, "") == "MSIE8.0") {
    alert("IE 8.0")
} else if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.split(";")[1].replace(/[ ]/g, "") == "MSIE9.0") {
    alert("IE 9.0")
} 
</script>

第三种：

<script type = "text/javascript">
if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/7./i) == "7.") {
    alert("IE 7.0");
} else if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/8./i) == "8.") {
    alert("IE 8.0");
} else if (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.match(/9./i) == "9.") {
    alert("IE 9.0");
} else if (navigator.appName == "Microsoft Internet Explorer") {
    alert("IE 6.0");
} 
</script>