I once had the same problem.
I created a little function to help me out. Don't know where it is but I managed to recreate it:
function get(item,url) {
if (url == undefined)
url = window.location.href;
var itemlen = item.length
var items = url.split('?')[1].split('&');
for (var i = 0, len = items.length;i<len;i++) {
if (items[i].substr(0,itemlen) == item)
return items[i].split('=')[1];
}
return null;
}
So you would use it like:
get('bi');
If the url you gave was your current url, if not you could do:
get('bi','http://www.abebooks.com/servlet/BookDetailsPL?bi=1325819827&searchurl=an%3DLofting%252C%2BHugh.%26ds%3D30%26sortby%3D13%26tn%3DDOCTOR%2BDOLITTLE%2527S%2BGARDEN.')
Hope I didn't leave in any bugs :)