How to integrate firebase-auth to verify phone number - firebase

Question

I have created phone number verify screen and now I want to integrate firebase-auth for verifying phone number via OTP. But I have no idea how to do that, Please help me with it.
I have tried to find tutorial and example, but those were not helpful for me.
Phone Verify Screen
import React from 'react';
import {StyleSheet, View, TextInput, TouchableOpacity, Text, KeyboardAvoidingView, BackHandler, Alert, AsyncStorage, ToastAndroid } from 'react-native';
import HandleBack from '../component/backHandler';
import * as firebase from 'firebase';
class BuyerVerify extends React.Component{
componentDidMount(){
this.getData();
};
onBack = () => {
return true;
};
getData = () => {
const getNumber = async () => {
let number = '';
try {
number = await AsyncStorage.getItem('number');
} catch (error) {
// Error retrieving data
console.log(error.message);
}
//return number;
alert(number);
}
getNumber();
};
render(){
return(
<HandleBack onBack={this.onBack}>
<View style={styles.root}>
<View style={styles.outer}>
<View style={styles.inner}>
<KeyboardAvoidingView style={styles.container}>
<TextInput style={styles.input}
placeholder="Enter OTP"
placeholderTextColor="#939eaf"
keyboardType="phone-pad"
/>
<TouchableOpacity style={styles.button1Container}>
<Text style={styles.buttonText}>
Verify Buyer
</Text>
</TouchableOpacity>
<TouchableOpacity style={styles.button2Container} onPress={()=> this.props.navigation.navigate('Main')}>
<Text style={styles.buttonText}>
Change number
</Text>
</TouchableOpacity>
</KeyboardAvoidingView>
</View>
</View>
</View>
</HandleBack>
);
}
}
export default BuyerVerify;
I want to verify phone number via OTP using firebase.

Answer 1

From Firebase's PhoneAuthProvider interface:
// 'recaptcha-container' is the ID of an element in the DOM.
var applicationVerifier = new firebase.auth.RecaptchaVerifier(
'recaptcha-container');
var provider = new firebase.auth.PhoneAuthProvider();
provider.verifyPhoneNumber('[phone]', applicationVerifier)
.then(function(verificationId) {
var verificationCode = window.prompt('Please enter the verification ' +
'code that was sent to your mobile device.');
return firebase.auth.PhoneAuthProvider.credential(verificationId,
verificationCode);
})
.then(function(phoneCredential) {
return firebase.auth().signInWithCredential(phoneCredential);
});