js read firestore database code example

Example 1: firestore set a document

let data = {
  name: 'Los Angeles',
  state: 'CA',
  country: 'USA'
};

// Add a new document in collection "cities" with ID 'LA'
let setDoc = db.collection('cities').doc('LA').set(data);

Example 2: get data from firestore

const [hospitalsDetails, setHospitalsDetails] = useState([])
    useEffect(()=>{
        //load hospitals into hospitalsList
        const hospitals = []
        db.collection('Hospitals').get()
            .then(snapshot => {
                snapshot.docs.forEach(hospital => {
                    let currentID = hospital.id
                    let appObj = { ...hospital.data(), ['id']: currentID }
                    hospitals.push(appObj)

                    hospitals.push(hospital.data())
            })
            setHospitalsDetails(hospitals)
        })
    },[])