How do you insert a document into a MongoDB collection?

Call insertOne() on the collection, passing the document as a plain JavaScript object.

await birthdays.insertOne({
  name: "Anna",
  day: new Date("1985-03-21")
});

• The object can contain nested objects and arrays
• MongoDB automatically adds an _id field if not provided
• Returns a result object with insertedId

Go deeper:

• db.collection.insertOne() (MongoDB Manual) — full signature, the auto-generated ObjectId, and the returned insertedId.