How to remove a Firebase listener in React

To remove a Firebase listener in React, use the off() function.

jsx
import React, { useEffect, useState } from 'react';
import firebase                       from './Firebase';

const Views = () => {

    const [views, setViews] = useState(0);

    useEffect( () => {

        // Defining path
        let ref = firebase.database().ref('views');
        
        // Declaring listener
        let listener = ref.on('value', snapshot => {

            if(snapshot.val()){

                setViews(snapshot.val());

            }

        });
        
        // Removing listener
        return () => ref.off('value', listener);

    }, []);


    return (
        <div className = 'Views'>
            <div>Number of views:  {views}</div>
        </div>
    );

}

export default Views;