Add a new image with the existing image list in firestore database

I have already two images in the firestore database, I am trying to add a new image to this list? How can I add a new image to the existing image list?

Answer

To add another array to the postImg, you can:

const db = firebase.firestore();
const colRef = db.collection("[e-mail]");
const docRef = colRef.doc("1fJBcGT8DlZdgbl01LeX");
docRef.update({
  postImg: firebase.firestore.FieldValue.arrayUnion("thenewurl");
})

Also see the Firebase documentation on adding items to an array.