How to check if device has sensor for authentication with biometrics? (react-native-fingerprint-scanner)

I am using this library to authenticate with biometrics sensor such as face ID or fingerprint scanner but I would like to know how to detect whether the device has a sensor or not : react-native-fingerprint-scanner

according to it's documentation there is an API called .isSensorAvailable() but I dont understand what does it return in case there isn't any available sensor in the device.

You can use the .isSensorAvailable() API like this example below.

import FingerprintScanner from 'react-native-fingerprint-scanner'

    FingerprintScanner
                .isSensorAvailable()
                .then(() => {
                // Call the Fingerprint Scanner Method
                    FingerprintScanner
                        .authenticate({ description: 'Authenticate to access this' })
                        .then(() => {
                            // Method for Authentication
                            onAuthenticate()
                        })
                        // Call error method
                        .catch(error => onAuthenticationFailure(error))

                })
                 //Call the error method
                .catch(error => onAuthenticationFailure(error))