File system access in React Native - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the react-native-fs library?

It provides an easy way to read, write, and manage files on a device's file system in React Native apps.

beginner

How do you read a text file asynchronously using react-native-fs?

Use RNFS.readFile(path, 'utf8') which returns a promise with the file content as a string.

intermediate

What is the difference between DocumentDirectoryPath and ExternalDirectoryPath in React Native file system?

DocumentDirectoryPath is private app storage, backed up and sandboxed. ExternalDirectoryPath is public external storage, accessible by other apps (Android only).

beginner

Why should you handle permissions when accessing the file system on mobile devices?

Because mobile OSes restrict file access for security. You must request user permission to read/write files outside your app sandbox.

beginner

What method would you use to check if a file exists before reading it in React Native?

Use RNFS.exists(path) which returns a promise resolving to true if the file exists, false otherwise.

Which React Native library is commonly used for file system access?

A react-native-gesture-handler

B react-native-fs

C react-native-maps

D react-native-camera

react-native-fs is the library designed for file system operations like reading and writing files.

What does RNFS.readFile(path, 'utf8') return?

A A string with file contents

B A boolean indicating success

C An error object

D A promise resolving to file contents

This method returns a promise that resolves to the file contents as a string.

Which directory path is private and sandboxed for your app?

A CacheDirectoryPath

B ExternalDirectoryPath

C DocumentDirectoryPath

D TemporaryDirectoryPath

DocumentDirectoryPath is private app storage, safe from other apps.

Before reading a file, which method helps you check if it exists?

A RNFS.exists

B RNFS.readFile

C RNFS.writeFile

D RNFS.unlink

RNFS.exists(path) returns true if the file exists, helping avoid errors.

Why must you request permissions for file system access on mobile?

A For security and privacy reasons

B To access internet

C To improve app speed

D To enable push notifications

Mobile OSes restrict file access to protect user data, so apps must ask permission.

Explain how to read a text file in React Native using react-native-fs.

Think about asynchronous file reading with promises.

Describe the difference between private and external storage paths in React Native file system.

Consider where files are stored and who can access them.