<html>
<head>
</head>
<body>
<script>
var url='pagename?para=xx¶3=fasfaf¶4=dfa';
function changeURLPar(destiny, par, par_value)
{
var pattern = par+'=([^&]*)';
var replaceText = par+'='+par_value;
if (destiny.match(pattern))
{
var tmp = '/\\'+par+'=[^&]*/';
tmp = destiny.replace(eval(tmp), replaceText);
return (tmp);
}
else
{
if (destiny.match('[\?]'))
{
return destiny+'&'+ replaceText;
}
else
{
return destiny+'?'+replaceText;
}
}
return destiny+'\n'+par+'\n'+par_value;
}
alert(changeURLPar(url,'para','99'))
</script>
</body>
</html>