我想在方法中CRUD FireStore的值

const db = firebase.firestore();
const usersRef = db.collection("users");

usersRef.add({
  name: "John",
  age: 25,
  email: "john@example.com"
})
.then((docRef) => {
  console.log("Document written with ID: ", docRef.id);
})
.catch((error) => {
  console.error("Error adding document: ", error);
});

const db = firebase.firestore();
const usersRef = db.collection("users");

usersRef.where("name", "==", "John")
  .get()
  .then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
      console.log(doc.id, " => ", doc.data());
    });
  })
  .catch((error) => {
    console.error("Error getting documents: ", error);
  });

const db = firebase.firestore();
const usersRef = db.collection("users");

usersRef.doc("documentId")
  .update({
    age: 30
  })
  .then(() => {
    console.log("Document successfully updated!");
  })
  .catch((error) => {
    console.error("Error updating document: ", error);
  });

const db = firebase.firestore();
const usersRef = db.collection("users");

usersRef.doc("documentId")
  .delete()
  .then(() => {
    console.log("Document successfully deleted!");
  })
  .catch((error) => {
    console.error("Error deleting document: ", error);
  });