I want to implement change password functionality for my application.
Projects created at console.firebase.google.com must use the new Firebase Authentication SDKs available from firebase.google.com/docs/auth/
There is no way to retrieve the current password of a user from Firebase Authentication.
One way to allow your users to change their password is to show a dialog where they enter their current password and the new password they'd like. You then sign in (or re-authenticate) the user with the current passwordand call
updatePassword() to update it.