This module is a wrapper around zxcvbn4j and zxcvbn-ios.
Why? Because js module huge.
$ yarn add react-native-zxcvbn
This module supports autolinking so if you use RN 0.60+ then no additional action is required.
Otherwise, run
$ react-native link react-native-zxcvbn
import { score } from 'react-native-zxcvbn';
const strength = await score(password);
console.log(strength); // 0-4