js页面跳转常用的几种方式

<script language="javascript" type="text/javascript"> 
window.location.href="jb51.jsp?backurl="+window.location.href; 
</script> 

<script language="javascript"> 
alert("返回"); 
window.history.back(-1); 
</script> 

<script language="javascript"> 
window.navigate("jb51.jsp"); 
</script> 

<script language="JavaScript"> 
self.location=‘jb51.htm‘; 
</script> 

<script language="javascript"> 
alert("非法访问！"); 
top.location=‘jb51.jsp‘; 
</script> 

<script language="javascript" type="text/javascript"> 
function request(paras){ 
var url = location.href; 
var paraString = url.substring(url.indexOf("?")+1,url.length).split("&"); 
var paraObj = {} 
for (i=0; j=paraString[i]; i++){ 
paraObj[j.substring(0,j.indexOf("=")).toLowerCase()] = j.substring(j.indexOf("=")+1,j.length); 
} 
var returnValue = paraObj[paras.toLowerCase()]; 
if(typeof(returnValue)=="undefined"){ 
return ""; 
}else{ 
return returnValue; 
} 
} 
var theurl 
theurl=request("url"); 
if (theurl!=‘‘){ 
location=theurl 
} 
</script>