thisURL = document.URL
thisHREF = document.location.href
thisSLoc = self.location.href
thisDLoc = document.location
strwrite = " thisURL: [" + thisURL + "]<br />"
strwrite += " thisHREF: [" + thisHREF + "]<br />"
strwrite += " thisSLoc: [" + thisSLoc + "]<br />"
strwrite += " thisDLoc: [" + thisDLoc + "]<br />"
document.write( strwrite )
</script>
<script type="text/javascript">
thisTLoc = top.location.href
thisPLoc = parent.document.location
thisTHost = top.location.hostname
thisHost = location.hostname
strwrite = " thisTLoc: [" + thisTLoc + "]<br />"
strwrite += " thisPLoc: [" + thisPLoc + "]<br />"
strwrite += " thisTHost: [" + thisTHost + "]<br />"
strwrite += " thisHost: [" + thisHost + "]<br />"
document.write( strwrite )
</script>
<script type="text/javascript">
tmpHPage = thisHREF.split( "/" )
thisHPage = tmpHPage[ tmpHPage.length-1 ]
tmpUPage = thisURL.split( "/" )
thisUPage = tmpUPage[ tmpUPage.length-1 ]
strwrite = " thisHPage: [" + thisHPage + "]<br />"
strwrite += " thisUPage: [" + thisUPage + "]<br />"
document.write( strwrite )
</script>
不清楚你说的根目录是哪个根目录，JavaScript运行于浏览器沙盒模式中，无法和系统进行交互，所以你就别指望能直接获取物理计算机的磁盘目录了，如果是获取url的某曾目录，可以使用正则表达式匹配，或者检索字符串等等。
