jQuery.query = function(s) {
    var r = {};
    if (s) {
        var q = s.substring(s.indexOf('?') + 1); // remove everything up to the ?
        q = q.replace(/\&$/, ''); // remove the trailing &
        jQuery.each(q.split('&'), function() {
            var splitted = this.split('=');
            var key = splitted[0];
            var val = splitted[1];
            // convert numbers
            if (/^[0-9.]+$/.test(val)) val = parseFloat(val);
            // convert booleans
            if (val == 'true') val = true;
            if (val == 'false') val = false;
            // ignore empty values
            if (typeof val == 'number' || typeof val == 'boolean' || val.length > 0) r[key] = val;
        });
    }
    return r;
};

//Exemplo de uso
//url = http://localhost:1569/FormularioPreencher.aspx?idCampo=65
//var query = $.query(location.search).idCampo;
//query vale 65!