Breaking News: Grepper is joining You.com. Read the official announcement!

useLocalStorage react hook

Mehedi Islam Ripon answered on February 10, 2023 Popularity 9/10 Helpfulness 2/10

answer useLocalStorage react hook

useLocalStorage react hook

Comment

import {
  Dispatch,
  SetStateAction,
  useCallback,
  useEffect,
  useState,
} from 'react'

import { useEventCallback, useEventListener } from 'usehooks-ts'

declare global {
  interface WindowEventMap {
    'local-storage': CustomEvent
  }
}

type SetValue<T> = Dispatch<SetStateAction<T>>

function useLocalStorage<T>(key: string, initialValue: T): [T, SetValue<T>] {
  // Get from local storage then
  // parse stored json or return initialValue
  const readValue = useCallback((): T => {
    // Prevent build error "window is undefined" but keeps working
    if (typeof window === 'undefined') {
      return initialValue
    }

    try {
      const item = window.localStorage.getItem(key)
      return item ? (parseJSON(item) as T) : initialValue
    } catch (error) {
      console.warn(`Error reading localStorage key “${key}”:`, error)
      return initialValue
    }
  }, [initialValue, key])

  // State to store our value
  // Pass initial state function to useState so logic is only executed once
  const [storedValue, setStoredValue] = useState<T>(readValue)

  // Return a wrapped version of useState's setter function that ...
  // ... persists the new value to localStorage.
  const setValue: SetValue<T> = useEventCallback(value => {
    // Prevent build error "window is undefined" but keeps working
    if (typeof window === 'undefined') {
      console.warn(
        `Tried setting localStorage key “${key}” even though environment is not a client`,
      )
    }

    try {
      // Allow value to be a function so we have the same API as useState
      const newValue = value instanceof Function ? value(storedValue) : value

      // Save to local storage
      window.localStorage.setItem(key, JSON.stringify(newValue))

      // Save state
      setStoredValue(newValue)

      // We dispatch a custom event so every useLocalStorage hook are notified
      window.dispatchEvent(new Event('local-storage'))
    } catch (error) {
      console.warn(`Error setting localStorage key “${key}”:`, error)
    }
  })

  useEffect(() => {
    setStoredValue(readValue())
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [])

  const handleStorageChange = useCallback(
    (event: StorageEvent | CustomEvent) => {
      if ((event as StorageEvent)?.key && (event as StorageEvent).key !== key) {
        return
      }
      setStoredValue(readValue())
    },
    [key, readValue],
  )

  // this only works for other documents, not the current one
  useEventListener('storage', handleStorageChange)

  // this is a custom event, triggered in writeValueToLocalStorage
  // See: useLocalStorage()
  useEventListener('local-storage', handleStorageChange)

  return [storedValue, setValue]
}

export default useLocalStorage

// A wrapper for "JSON.parse()"" to support "undefined" value
function parseJSON<T>(value: string | null): T | undefined {
  try {
    return value === 'undefined' ? undefined : JSON.parse(value ?? '')
  } catch {
    console.log('parsing error on', { value })
    return undefined
  }
}

Popularity 9/10 Helpfulness 2/10 Language javascript

Source: Grepper

Tags: hook javascript

Link to this answer
Share Copy Link

Contributed on Feb 10 2023

Mehedi Islam Ripon

0 Answers Avg Quality 2/10

useLocalStorage react hook

Contents

More Related Answers

useLocalStorage react hook

Grepper

Documentation

Social

Legal

Contact

Oops, You will need to install Grepper and log-in to perform this action.