Firestore - Listen to specific field change?

Question

How can I listen to a specific field change with firestore js sdk ?

In the documentation, they only seem to show how to listen for the whole document, if any of the

Answer 1

Just out of the box what I do is watching before and after with the before and after method

const clientDataBefore = change.before.data();
console.log("Info database before ", clientDataBefore);

const clientDataAfter = change.after.data();
console.log("Info database after ", clientDataAfter );

For example now you should compare the changes for a specific field and do some actions or just return it.

Some more about before.data() and after.data() here