function isEmpty(v) {
    switch (typeof v) {
        case 'undefined':
            return true;
        case 'string':
            if (v.replace(/(^[ \t\n\r]*)|([ \t\n\r]*$)/g, '').length == 0) return true;
            break;
        case 'boolean':
            if (!v) return true;
            break;
        case 'number':
            if (0 === v || isNaN(v)) return true;
            break;
        case 'object':
            if (null === v || v.length === 0) return true;
            for (var i in v) {
                return false;
            }
            return true;
    }
    return false;
}