const emailExists = (email) => {

  // Assuming you have already initialized Firebase and have a reference to the Firebase database

​

  return new Promise((resolve, reject) => {

    const emailRef = firebase.database().ref('users').orderByChild('email').equalTo(email);

​

    // Listen for value changes in the emailRef

    emailRef.on('value', (snapshot) => {

      if (snapshot.exists()) {

        resolve(true); // Email exists in the database

      } else {

        resolve(false); // Email does not exist in the database

      }

    }, (error) => {

      reject(error); // Error occurred while checking email existence

    });

  });

};

​

// Usage:

emailExists('example@example.com')

  .then((exists) => {

    console.log(exists); // true if email exists, false otherwise

  })

  .catch((error) => {

    console.error(error); // Handle error

  });