query_string.js

var QueryString = function () {
    var query_string = {},
        query = window.location.search.substring(1),
        vars = query.split("&");

    for (var i=0;i<vars.length;i++) {
        var pair = vars[i].split("=");
        if (typeof query_string[pair[0]] === "undefined") {
            query_string[pair[0]] = pair[1];
        } else if (typeof query_string[pair[0]] === "string") {
            var arr = [ query_string[pair[0]], pair[1] ];
            query_string[pair[0]] = arr;
            // If third or later entry with this name
        } else {
            query_string[pair[0]].push(pair[1]);
        }
    }

    return query_string;
}();