react-native-session-storage

Session Storage like module for React Native for session-bound storage.

This module is NOT an alternative for Async Storage which is meant for persistent storage. Instead, this module provides a "volatile" session-bound storage which gets cleared when the app is re-opened.

Installation

With npm:

npm install react-native-session-storage

With yarn:

yarn add react-native-session-storage

With Expo CLI:

expo install react-native-session-storage

Usage

Importing

import SessionStorage from 'react-native-session-storage';

API Reference

Basic Operations

Method	Description	Parameters	Return Type
setItem	Store a key-value pair	key: string, value: any	void
getItem	Get value by key	key: string	any or undefined
removeItem	Remove value by key	key: string	void
clear	Clear all key-value pairs	-	void
key	Get key name by index	n: number	string or undefined
length	Get number of stored key-value pairs	-	number

Advanced Operations

Method	Description	Parameters	Return Type
multiGet	Get multiple values by their keys	keys: string[]	`Record<string, any
getAllItems	Get all key-value pairs	-	Record<string, any>
multiSet	Store multiple key-value pairs	`keyValuePairs: [string, any][]	Record<string, any>`
mergeItem	Merge an object with existing value	key: string, value: Record<string, unknown>	`Record<string, unknown>
multiMerge	Merge multiple objects with their values	`keyValuePairs: [string, Record<string, unknown>][]	Record<string, Record<string, unknown>>`
multiRemove	Remove multiple values by their keys	keys: string[]	void
getAllKeys	Get all keys	-	string[]

Examples

Basic Usage

// Storing data
SessionStorage.setItem('@storage_key', 'stored value');
SessionStorage.setItem('@user', { name: 'John', age: 30 });

// Reading data
const value = SessionStorage.getItem('@storage_key'); // 'stored value'
const user = SessionStorage.getItem('@user'); // { name: 'John', age: 30 }

// Removing data
SessionStorage.removeItem('@storage_key');

// Clearing all data
SessionStorage.clear();

// Get key by index
const firstKey = SessionStorage.key(0);

// Get storage size
const size = SessionStorage.length;

Advanced Usage

// Working with multiple items
SessionStorage.multiSet([
  ['@key1', 'value1'],
  ['@key2', 'value2'],
  ['@key3', { complex: 'object' }]
]);

// Getting multiple items
const values = SessionStorage.multiGet(['@key1', '@key2', '@key3']);
console.log(values); // { '@key1': 'value1', '@key2': 'value2', '@key3': { complex: 'object' } }

// Getting all items
const allData = SessionStorage.getAllItems();

// Merging objects
SessionStorage.setItem('@user', { name: 'John', age: 30 });
const merged = SessionStorage.mergeItem('@user', { age: 31, location: 'NYC' });
console.log(merged); // { name: 'John', age: 31, location: 'NYC' }

// Multiple merge operations
SessionStorage.multiMerge({
  '@user1': { role: 'admin' },
  '@user2': { status: 'active' }
});

// Getting all keys
const allKeys = SessionStorage.getAllKeys();

// Removing multiple items
SessionStorage.multiRemove(['@key1', '@key2']);

TypeScript Support

The module is written in TypeScript and supports generics for better type safety:

// Type-safe storage
interface User {
  name: string;
  age: number;
  email: string;
}

// Create a typed storage instance (not available in the default export)
import { Storage } from 'react-native-session-storage';
const UserStorage = new Storage<User>();

// Type-safe operations
UserStorage.setItem('@user1', { name: 'John', age: 30, email: 'john@example.com' });

// TypeScript will ensure you get the correct type back
const user: User | undefined = UserStorage.getItem('@user1');

Applications

API Response Caching

import SessionStorage from 'react-native-session-storage';

const fetchData = async (endpoint) => {
  // Check if response is already cached
  const cachedResponse = SessionStorage.getItem(`@api_cache_${endpoint}`);
  
  if (cachedResponse) {
    console.log('Using cached response');
    return cachedResponse;
  }
  
  // Fetch new data
  try {
    const response = await fetch(`https://api.example.com/${endpoint}`);
    const data = await response.json();
    
    // Cache the response
    SessionStorage.setItem(`@api_cache_${endpoint}`, data);
    
    return data;
  } catch (error) {
    console.error('Fetch error:', error);
    throw error;
  }
};

Memoization Provider

import SessionStorage from 'react-native-session-storage';

// Create a memoized function with SessionStorage as cache
const memoize = (fn) => {
  return (...args) => {
    const key = `@memo_${fn.name}_${JSON.stringify(args)}`;
    
    // Check if result is already cached
    const cachedResult = SessionStorage.getItem(key);
    
    if (cachedResult !== undefined) {
      return cachedResult;
    }
    
    // Calculate and cache result
    const result = fn(...args);
    SessionStorage.setItem(key, result);
    
    return result;
  };
};

// Example usage
const expensiveCalculation = (a, b) => {
  console.log('Performing expensive calculation');
  return a * b;
};

const memoizedCalculation = memoize(expensiveCalculation);

// First call will perform calculation
const result1 = memoizedCalculation(5, 10); // Logs: Performing expensive calculation

// Second call with same args will use cached result
const result2 = memoizedCalculation(5, 10); // No log, returns cached result

// Different args will perform calculation again
const result3 = memoizedCalculation(7, 8); // Logs: Performing expensive calculation

Form State Persistence

import SessionStorage from 'react-native-session-storage';
import { useState, useEffect } from 'react';

const useSessionForm = (formId, initialState = {}) => {
  // Get stored form state or use initial state
  const [formState, setFormState] = useState(() => {
    const stored = SessionStorage.getItem(`@form_${formId}`);
    return stored || initialState;
  });
  
  // Update storage when state changes
  useEffect(() => {
    SessionStorage.setItem(`@form_${formId}`, formState);
  }, [formId, formState]);
  
  // Clear form data
  const resetForm = () => {
    SessionStorage.removeItem(`@form_${formId}`);
    setFormState(initialState);
  };
  
  return [formState, setFormState, resetForm];
};

// Example usage in a component
function SignupForm() {
  const [formData, setFormData, resetForm] = useSessionForm('signup', {
    email: '',
    name: '',
    agreed: false
  });
  
  const handleChange = (field, value) => {
    setFormData({ ...formData, [field]: value });
  };
  
  // Form state persists during the app session
  // Users can navigate away and come back with data intact
  
  return (
    // Form UI implementation
  );
}

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT

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