firebase db colleciton set code example
Example 1: firestore set a document
let data = {
name: 'Los Angeles',
state: 'CA',
country: 'USA'
};
// Add a new document in collection "cities" with ID 'LA'
let setDoc = db.collection('cities').doc('LA').set(data);
Example 2: document.set() firebasefirestore java
var washingtonRef = db.collection("cities").doc("DC");// Atomically add a new region to the "regions" array field.washingtonRef.update({ regions: firebase.firestore.FieldValue.arrayUnion("greater_virginia")});// Atomically remove a region from the "regions" array field.washingtonRef.update({ regions: firebase.firestore.FieldValue.arrayRemove("east_coast")});