Sample code to read file system in React

App.js

import * as FileSystem from 'expo-file-system';

        <Button
          onPress={() => {
            let dirToRead = FileSystem.documentDirectory;
            console.log('Reading :' + dirToRead);
            
            FileSystem.readDirectoryAsync('file://' + dirToRead)
              .then((dir) => {
                dir.forEach((val) => {
                  console.log('File: ' + val);
                });
              })
              .catch(() => {
                console.log('Error reading directory: ' + dirToRead);
              });
          }}
          title="click me"
        />