The part of the URL that is from the questionmark onwards is called a query string.
Here is a pure JavaScript function to parse the query string to obtain particular values:
function querystring(key)
{
var filter;
var value;
key = key.replace(/[\[]/, '\\\[').replace(/[\]]/, '\\\]');
filter = new RegExp('[\\?&]' + key + '=([^&#]*)');
value = filter.exec(window.location.search);
if(value == null)
{
return '';
}
else
{
return decodeURIComponent(value[1].replace(/\+/g, ' '));
}
}
You just pass in the query string key name you're interested in (as a string) and you get the value back (also as a string.) An example of how you could use the function:
alert('Category = ' + querystring('catagory'));