$each mongodb code example

Example 1: mongodb push to arry in update

db.collection.update({_id:xx}, {$push:{letters : {$each:['first one'], $position:0}}})

Example 2: how to spread an array in mongodb

db.inventory.update(
   { _id: 2 },
   { $addToSet: { tags: { $each: [ "camera", "electronics", "accessories" ] } } }
 )