Using FirebaseArray to signup and login

Hi Everyone, I am pretty new to Angular. I was trying to create a simple login and sign up page in the ionic creator. When I am signing up I take name, email, and password and I am uploading it to my real-time database. To get the data I use a firebasearray. This works and I am able to get the data as well as upload it, but the problem I am facing is I am unable to parse the firebasearray to check if the current email currently exists in it or not. I tried for each loop and tried with firebase functions like getRecord and keyAt. Nothing seems to work, any help would be appreciated!