gistfile1.js

function getQueryString(key)
{
    var url   = window.location.href,
        pairs = url.slice(url.indexOf('?') + 1).split('&'),
        qs    = window.location.qs || {},
        kv;

    if (! qs.cached){
        for (var i=0, l=pairs.length; i<l; i++){
            kv = pairs[i].split('=');
            qs[unescape(kv[0])] = unescape(kv[1]);
        }
        qs.cached = true;
        window.location.qs = qs;
    }

    return key ? qs[key] : qs;
}