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import { Dispatch, SetStateAction, useEffect, useState } from 'react'
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 = (): T => {
// Prevent build error "window is undefined" but keep keep working
if (typeof window === 'undefined') {
return initialValue
}
try {
const item = window.localStorage.getItem(key)
return item ? (JSON.parse(item) as T) : initialValue
} catch (error) {
console.warn(`Error reading localStorage key “${key}”:`, error)
return initialValue
}
}
// State to store our value
// Pass initial state function to useState so logic is only executed once
const [storedValue, setStoredValue] = useState<T>(readValue)
// Return a wrapped version of useState's setter function that ...
// ... persists the new value to localStorage.
const setValue: SetValue<T> = value => {
// Prevent build error "window is undefined" but keeps working
if (typeof window == 'undefined') {
console.warn(`Tried setting localStorage key “${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
}, [])
useEffect(() => {
const handleStorageChange = () => {
setStoredValue(readValue())
}
// this only works for other documents, not the current one
window.addEventListener('storage', handleStorageChange)
// this is a custom event, triggered in writeValueToLocalStorage
window.addEventListener('local-storage', handleStorageChange)
return () => {
window.removeEventListener('storage', handleStorageChange)
window.removeEventListener('local-storage', handleStorageChange)
}
// eslint-disable-next-line react-hooks/exhaustive-deps
}, [])
return [storedValue, setValue]
}
export default useLocalStorage
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