use-storage-backed-state

useStorageBackedState

Custom React hook for state management like useState but persisted to localStorage. Check interactive demo.

Installation

npm install use-storage-backed-state

How to use

import React from 'react'
import { useStorageBackedState } from 'use-storage-backed-state'

export const MyComponent = () => {
	const [count, setCount] = useStorageBackedState({
		key: 'count',
		defaultValue: 0,
	})

	return (
		<section>
			<h1>
				Value: <output>{count}</output>
			</h1>
			<button
				onClick={() => {
					setCount(count + 1)
				}}
			>
				increment
			</button>
			<button
				onClick={() => {
					setCount(count - 1)
				}}
			>
				decrement
			</button>
		</section>
	)
}

Notes

• Stores data in localStorage.

• Works with sessionStorage too.

  useStorageBackedState({
      // …
      storage: sessionStorage,
  })

• Realtime synchronization between multiple uses with the same key. Even across tabs.

• You can opt out from storage and synchronization by passing null to storage option.

  const [count, setCount] = useStorageBackedState({
      key: 'local-count',
      initialValue: 1,
      storage: null,
  })

Advanced Usage

Custom parser and serializer

By default, use-storage-backed-state uses JSON.stringify and JSON.parse to handle values. You can provide your own functions to handle custom data types, like Date objects.

const [date, setDate] = useStorageBackedState({
	key: 'my-date',
	defaultValue: new Date(),
	parse: (value) => new Date(value),
	stringify: (value) => value.toISOString(),
})

Usage outside of React component

You can also get, set, and remove values from outside of a React component.

import {
	getStorageBackedValue,
	setStorageBackedValue,
	removeStorageBackedValue,
} from 'use-storage-backed-state'

// Set a value
setStorageBackedValue({ key: 'my-key', value: 'my-value' })

// Get a value
const value = getStorageBackedValue({ key: 'my-key', defaultValue: 'default' })

// Remove a value
removeStorageBackedValue({ key: 'my-key' })

Subscribing to changes

You can subscribe to changes of a value. This is useful for integrating with other libraries like rxjs.

import { subscribeStorageBackedValue } from 'use-storage-backed-state'
import { Observable } from 'rxjs'

const myValue$ = new Observable((subscriber) => {
	const { unsubscribe } = subscribeStorageBackedValue({
		key: 'my-key',
		defaultValue: 'default',
		onChange: (value) => {
			subscriber.next(value)
		},
	})

	return unsubscribe
})

myValue$.subscribe((value) => {
	console.log('Value changed:', value)
})