Use Local Storage - Mantine

import { Layout } from '@/layout'; import { MDX_DATA } from '@/mdx';

export default Layout(MDX_DATA.useLocalStorage);

Usage

The use-local-storage hook allows you to use a value from localStorage as React state. The hook works the same way as useState, but also writes the value to localStorage:

tsx

import { useLocalStorage } from '@mantine/hooks';

// The hook will read the value from localStorage.getItem('color-scheme')
// If localStorage is not available or the value at a given key does not exist,
// 'dark' will be assigned to the value variable
const [value, setValue] = useLocalStorage({
  key: 'color-scheme',
  defaultValue: 'dark',
});

// The value is set both to state and localStorage at 'color-scheme'
setValue('light');

// You can also use a callback like in the useState hook to set the value
setValue((current) => (current === 'dark' ? 'light' : 'dark'));

Example

Example of a color scheme toggle button that uses use-local-storage hook to store current color scheme in the localStorage:

tsx

import { MoonStarsIcon, SunIcon } from '@phosphor-icons/react';
import { ActionIcon } from '@mantine/core';
import { useLocalStorage } from '@mantine/hooks';

function ColorSchemeToggle() {
  const [colorScheme, setColorScheme] = useLocalStorage<
    'light' | 'dark'
  >({
    key: 'color-scheme',
    defaultValue: 'light',
  });

  const toggleColorScheme = () =>
    setColorScheme((current) =>
      current === 'dark' ? 'light' : 'dark'
    );

  return (
    <ActionIcon onClick={toggleColorScheme}>
      {colorScheme === 'dark' ? <SunIcon /> : <MoonStarsIcon />}
    </ActionIcon>
  );
}

Remove value

Use removeValue callback to clean localStorage/sessionStorage. When value is removed it is reset to defaultValue:

tsx

import { useLocalStorage } from '@mantine/hooks';

const [value, setValue, removeValue] = useLocalStorage({
  key: 'color-scheme',
  defaultValue: 'light',
});

Browser tabs synchronization

use-local-storage subscribes to storage event. When state changes in one tab, it automatically updates the value in all other opened browser tabs. You can test this feature by opening 2 tabs with Mantine docs side by side and changing the color scheme (button on the top right or ⌘ + J on MacOS and Ctrl + J on Windows and Linux).

Serialize/deserialize JSON

By default, the hook will serialize/deserialize data with JSON.stringify/JSON.parse. If you need to store data in local storage that cannot be serialized with JSON.stringify – provide your own serialization handlers:

tsx

import { useLocalStorage } from '@mantine/hooks';

const [value, setValue] = useLocalStorage({
  key: 'color-scheme',
  serialize: (value) => {
    /* return value serialized to string */
  },
  deserialize: (localStorageValue) => {
    /* parse localStorage string value and return value */
  },
});

Usage with superjson

superjson is compatible with JSON.stringify/JSON.parse but works for Date, Map, Set and BigInt:

tsx

import superjson from 'superjson';
import { useLocalStorage } from '@mantine/hooks';

const defaultValue = { name: 'John', age: 25 };

const [value, setValue] = useLocalStorage({
  key: 'data',
  defaultValue,
  serialize: superjson.stringify,
  deserialize: (str) =>
    str === undefined ? defaultValue : superjson.parse(str),
});

use-session-storage

The use-session-storage hook works the same way as use-local-storage hook but uses sessionStorage instead of window.localStorage:

tsx

import { useSessionStorage } from '@mantine/hooks';

const [value, setValue] = useSessionStorage({
  key: 'session-key',
  defaultValue: 'mantine',
});

Set value type

You can specify value type same as in useState hook:

tsx

import { useLocalStorage } from '@mantine/hooks';

const [value, setValue] = useLocalStorage<'dark' | 'light'>({
  key: 'color-scheme',
  defaultValue: 'light',
});

Read storage value

To read value from storage without using hook, use readLocalStorageValue/readSessionStorageValue functions. Functions accept the same arguments as use-local-storage/use-session-storage hooks:

tsx

import { readLocalStorageValue } from '@mantine/hooks';

const value = readLocalStorageValue({ key: 'color-scheme' });

Definition

tsx

interface UseStorageOptions<T> {
  /** Local storage key */
  key: string;

  /** Default value that will be set if value is not found in local storage */
  defaultValue?: T;

  /** If set to true, value will be updated in useEffect after mount. Default value is true. */
  getInitialValueInEffect?: boolean;

  /** Determines whether the value must be synced between browser tabs, `true` by default */
  sync?: boolean;

  /** Function to serialize value into a string to be saved in local storage */
  serialize?: (value: T) => string;

  /** Function to deserialize string value from local storage to value */
  deserialize?: (value: string) => T;
}

type UseStorageReturnValue<T> = [
  T, // current value
  (val: T | ((prevState: T) => T)) => void, // callback to set value in storage
  () => void, // callback to remove value from storage
];

function useLocalStorage<T = string>(
  options: UseStorageOptions<T>,
): UseStorageReturnValue<T>;

Exported types

UseStorageOptions and UseStorageReturnValue types are exported from the @mantine/hooks package; you can import them in your application:

tsx

import type { UseStorageOptions, UseStorageReturnValue } from '@mantine/hooks';