Unless you are using one of the few web servers that employs server-side JavaScript, your script is going to run in the browser after the page is loaded. If you want to include information from the URL in your script (and this assumes that you can use a query string without changing the server's behavior), you can use window.location.search to get everything from the question mark onwards.
This function will return either the entire query string (without the question mark) or a semicolon-delimited list of values matching the name value you feed it:
function getUrlQueryString(param) {
var outObj = {};
var qs = window.location.search;
if (qs != "") {
qs = decodeURIComponent(qs.replace(/\?/, ""));
var paramsArray = qs.split("&");
var length = paramsArray.length;
for (var i=0; i<length; ++i) {
var nameValArray = paramsArray[i].split("=");
nameValArray[0] = nameValArray[0].toLowerCase();
if (outObj[nameValArray[0]]) {
outObj[nameValArray[0]] = outObj[nameValArray[0]] + ";" + nameValArray[1];
}
else {
if (nameValArray.length > 1) {
outObj[nameValArray[0]] = nameValArray[1];
}
else {
outObj[nameValArray[0]] = true;
}
}
}
}
var retVal = param ? outObj[param.toLowerCase()] : qs;
return retVal ? retVal : ""
}
So if the URL was, say:
http://www.yoursite.com/somepage.html?name=John%20Doe&occupation=layabout
if you call getUrlQueryString() you would get back name=John Doe&occupation=layabout. If you call getUrlQueryString("name"), you would get back John Doe.
(And yes, I like banner-style indents. So sue me.)