firestore add document with id code example

Example 1: firestore get id of new document

async function addCity(newCity) {
  const { id } = await db.collection("cities").add(newCity)
  console.log("the new city's id:", id)
}

Example 2: firestore create document with auto id

// Add a new document with a generated id.
db.collection("cities").add({
    name: "Tokyo",
    country: "Japan"
})
.then(function(docRef) {
    console.log("Document written with ID: ", docRef.id);
})
.catch(function(error) {
    console.error("Error adding document: ", error);
});
---------------------------
//If you want to specify id then use .set() 
// e.x   \/
db.collection("cities").doc("TYO").set({
    name: "Tokyo",
    country: "Japan"
})