expo-storage

A simple and efficient solution for persistent data storage in Expo/React Native applications, designed to overcome the size limitations of react-native async-storage by utilizing the expo-file-system.

Features

- No size limitations (unlike AsyncStorage)
- Simple, Promise-based API
- TypeScript support
- Persistent storage across app restarts
- JSON object support through automatic serialization
- Built-in security features
- Path traversal prevention
- Safe filename validation
- Automatic value serialization
- Directory existence checks
- Comprehensive error handling

Requirements

- Expo SDK 54 or newer
- React 19.0.0 or newer
- React Native 0.81.0 or newer
- expo-file-system 19.0.0 or newer

Installation

Using yarn:
``bash
yarn add expo-storage
`

Using expo:
`bash
expo install expo-storage
`

Usage

$3

`javascript
import { Storage } from 'expo-storage'
`

$3

#### Store Data

`javascript
try {
await Storage.setItem({
key: "myKey",
value: myValue // automatically serialized if not a string
})
} catch (error) {
// Handle invalid keys or storage failures
}
`

#### Retrieve Data

`javascript
try {
const item = await Storage.getItem({ key: "myKey" })
if (item !== null) {
const parsedItem = JSON.parse(item)
}
} catch (error) {
// Handle invalid keys or read failures
}
`

#### Delete Data

`javascript
try {
await Storage.removeItem({ key: "myKey" })
} catch (error) {
// Handle invalid keys or deletion failures
}
`

#### List All Keys

`javascript
try {
const keys = await Storage.getAllKeys()
} catch (error) {
// Handle listing failures
}
`

$3

#### Key Validation
- Keys must be non-empty strings
- Only alphanumeric characters, hyphens, underscores, and dots are allowed
- Path traversal attempts are blocked
- Invalid keys throw errors

#### Value Handling
- Automatic serialization of non-string values
- Safe JSON parsing
- Proper error propagation

#### Storage Directory
- Automatic creation of storage directory if needed
- Safe directory operations
- Path sanitization

$3

All methods may throw errors for:
- Invalid keys (non-alphanumeric or potential path traversal)
- File system operation failures
- Serialization failures for non-string values

Example error handling:
`javascript
try {
await Storage.setItem({
key: "user-preferences",
value: { theme: "dark" }
})
} catch (error) {
if (error.message.includes('Invalid storage key')) {
// Handle invalid key error
} else {
// Handle other storage errors
}
}
``

Storage Location

Data is stored in the app's document directory using expo-file-system, ensuring:
- Persistence across app restarts
- No size limitations
- Private storage accessible only to your app
- Safe file operations

Sample Projects

- WiSaw App: GitHub | Website

License

MIT License - See LICENSE file for details

Contributing

Issues and pull requests are welcome at the GitHub repository.