看看下面的代码是不是你想要的效果：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>无标题文档 </title>
</head>
<script type="text/javascript">
function setParam(key, value) {
var url = window.location;
var exp = new RegExp('^(.*)(\\\?|&)' + key + '=([^&]*)(.*)$');
var result = exp.exec(url);
if (result == null) {
window.location+= (window.location.search ? "&" : "?") + key + "=" + value;
} else {
window.location = result[1]+result[2]+key+"="+value+result[4];
}
}
</script>
<body><input type="text" id="key"/>
<input type="button" onclick="setParam('key', document.getElementById('key').value);" value="submit"/></body>
</html>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>无标题文档 </title>
</head>
<script type="text/javascript">
function setParam(key, value) {
var url = window.location;
var exp = new RegExp('^(.*)(\\\?|&)' + key + '=([^&]*)(.*)$');
var result = exp.exec(url);
if (result == null) {
window.location+= (window.location.search ? "&" : "?") + key + "=" + value;
} else {
window.location = result[1]+result[2]+key+"="+value+result[4];
}
}
</script>
<body><input type="text" id="key"/>
<input type="button" onclick="setParam('key', document.getElementById('key').value);" value="submit"/></body>
</html>
function changeparam(searchname, searchv)
{
var href=window.location.href;//网址全部地址
var vyes=window.location.search;//取地址栏所有参数,为空没有参数 if(vyes!='')//地址栏是否有参数
{//地址栏有参数
var r;
r=vyes.search(searchname);//参数出现的位置 if(r!=-1)//是否有这个参数
{//如果查询中有这个参数
var rtop,rend;
rtop=vyes.substr(0,r);//这个参数前面的参数
rend=vyes.substr(r);//这个参数及其后面的参数
var r2=rend.search('&');//后面参数连接符的位置
//var r2=searchname.length+searchv.length+1; if(r2!=-1)//这个参数后面是否有参数
{//这个参数后面有参数
rend=rend.substr(r2);//这个参数后面的参数
//alert(rtop+searchname+'='+searchv+rend);//新的参数
//alert(window.location.pathname);//不带参数的地址
location=window.location.pathname+rtop+searchname+'='+searchv+rend;
//return window.location.pathname+rtop+searchname+'='+searchv+rend;
}
else
{//如果后面没有&了.
location=window.location.pathname+rtop+searchname+'='+searchv;
//return window.location.pathname+rtop+searchname+'='+searchv;
}
}
else
{//如果没有这个参数,加上参数及其对应的值
location=href+'&'+searchname+'='+searchv;
//return href+'&'+searchname+'='+searchv;
}
}
else
{//地址栏没参数,加上参数及其对应的值
location=href+'?'+searchname+'='+searchv;
//return href+'?'+searchname+'='+searchv;
}
}
function hrefurl(searchname, searchv)
{//alert(searchv);
if(window.location.href != changeparam(searchname, searchv))
{alert(changeparam(searchname, searchv));
window.location == changeparam(searchname, searchv);
}
}
</script>