inc

db.inc(n) increments and decrements a field value.

increment field

await db.update({age: db.inc(3)}, "users", "bob")

// equivalent firestore
await fb.collection("users").doc("bob").update({age: firebase.firestore.FieldValue.increment(3)})

decrement field

use a negative number to decrement

await db.update({age: db.inc(-3)}, "users", "bob")

// equivalent firestore
await fb.collection("users").doc("bob").update({age: firebase.firestore.FieldValue.increment(-3)})