You can extract the key/value pairs from the location.search property, this property has the part of the URL that follows the ? symbol, including the ? symbol.
function getQueryString() {
var result = {}, queryString = location.search.slice(1),
re = /([^&=]+)=([^&]*)/g, m;
while (m = re.exec(queryString)) {
result[decodeURIComponent(m[1])] = decodeURIComponent(m[2]);
}
return result;
}
// ...
var myParam = getQueryString()["myParam"];