zustand/docs/guides/connect-to-state-with-url-hash.md

---
title: Connect to state with URL
nav: 11
---

## Connect State with URL Hash

If you want to connect state of a store to URL hash, you can create your own hash storage.

```ts
import { create } from 'zustand'
import { persist, StateStorage, createJSONStorage } from 'zustand/middleware'

const hashStorage: StateStorage = {
  getItem: (key): string => {
    const searchParams = new URLSearchParams(location.hash.slice(1))
    const storedValue = searchParams.get(key) ?? ''
    return JSON.parse(storedValue)
  },
  setItem: (key, newValue): void => {
    const searchParams = new URLSearchParams(location.hash.slice(1))
    searchParams.set(key, JSON.stringify(newValue))
    location.hash = searchParams.toString()
  },
  removeItem: (key): void => {
    const searchParams = new URLSearchParams(location.hash.slice(1))
    searchParams.delete(key)
    location.hash = searchParams.toString()
  },
}

export const useBoundStore = create()(
  persist(
    (set, get) => ({
      fishes: 0,
      addAFish: () => set({ fishes: get().fishes + 1 }),
    }),
    {
      name: 'food-storage', // unique name
      storage: createJSONStorage(() => hashStorage),
    },
  ),
)
```

## Persist and Connect State with URL Parameters (Example: URL Query Parameters)

There are times when you want to conditionally connect the state to the URL.
This example depicts usage of the URL query parameters
while keeping it synced with another persistence implementation, like `localstorage`.

If you want the URL params to always populate, the conditional check on `getUrlSearch()` can be removed.

The implementation below will update the URL in place, without refresh, as the relevant states change.

```ts
import { create } from 'zustand'
import { persist, StateStorage, createJSONStorage } from 'zustand/middleware'

const getUrlSearch = () => {
  return window.location.search.slice(1)
}

const persistentStorage: StateStorage = {
  getItem: (key): string => {
    // Check URL first
    if (getUrlSearch()) {
      const searchParams = new URLSearchParams(getUrlSearch())
      const storedValue = searchParams.get(key)
      return JSON.parse(storedValue as string)
    } else {
      // Otherwise, we should load from localstorage or alternative storage
      return JSON.parse(localStorage.getItem(key) as string)
    }
  },
  setItem: (key, newValue): void => {
    // Check if query params exist at all, can remove check if always want to set URL
    if (getUrlSearch()) {
      const searchParams = new URLSearchParams(getUrlSearch())
      searchParams.set(key, JSON.stringify(newValue))
      window.history.replaceState(null, '', `?${searchParams.toString()}`)
    }

    localStorage.setItem(key, JSON.stringify(newValue))
  },
  removeItem: (key): void => {
    const searchParams = new URLSearchParams(getUrlSearch())
    searchParams.delete(key)
    window.location.search = searchParams.toString()
  },
}

type LocalAndUrlStore = {
  typesOfFish: string[]
  addTypeOfFish: (fishType: string) => void
  numberOfBears: number
  setNumberOfBears: (newNumber: number) => void
}

const storageOptions = {
  name: 'fishAndBearsStore',
  storage: createJSONStorage<LocalAndUrlStore>(() => persistentStorage),
}

const useLocalAndUrlStore = create()(
  persist<LocalAndUrlStore>(
    (set) => ({
      typesOfFish: [],
      addTypeOfFish: (fishType) =>
        set((state) => ({ typesOfFish: [...state.typesOfFish, fishType] })),

      numberOfBears: 0,
      setNumberOfBears: (numberOfBears) => set(() => ({ numberOfBears })),
    }),
    storageOptions,
  ),
)

export default useLocalAndUrlStore
```

When generating the URL from a component, you can call buildShareableUrl:

```ts
const buildURLSuffix = (params, version = 0) => {
  const searchParams = new URLSearchParams()

  const zustandStoreParams = {
    state: {
      typesOfFish: params.typesOfFish,
      numberOfBears: params.numberOfBears,
    },
    version: version, // version is here because that is included with how Zustand sets the state
  }

  // The URL param key should match the name of the store, as specified as in storageOptions above
  searchParams.set('fishAndBearsStore', JSON.stringify(zustandStoreParams))
  return searchParams.toString()
}

export const buildShareableUrl = (params, version) => {
  return `${window.location.origin}?${buildURLSuffix(params, version)}`
}
```

The generated URL would look like (here without any encoding, for readability):

`https://localhost/search?fishAndBearsStore={"state":{"typesOfFish":["tilapia","salmon"],"numberOfBears":15},"version":0}}`

### Demo

- Hash: https://stackblitz.com/edit/vitejs-vite-9vg24prg
- Query: https://stackblitz.com/edit/vitejs-vite-hyc97ynf