Element.update(
{ _id: { $in: ['id1', 'id2', 'id3'] } },
{ $set: { visibility : yourvisibility } },
{multi: true}
)
You can not update two documents at once with a MongoDB query. You will always have to do that in two queries. You can of course set a value of a field to the same value, or increment with the same number, but you can not do two distinct updates in MongoDB with the same query.