Sync Zustand State Across Tabs Instantly

In complex web applications, maintaining a single, consistent state across multiple browser tabs or windows is a critical challenge. If a user updates their profile in Tab A, Tab B shouldn't be showing stale data.

The standard zustand/middleware/persist is great for persistence after a refresh, but it doesn't handle instant cross-tab synchronization out of the box.

The solution? A lightweight middleware that leverages the Broadcast Channel API (or the storage event for a similar effect) to communicate changes instantly between same-origin tabs.

I highly recommend libraries like zustand-sync-tabs or persist-and-sync. They turn a complex problem into a clean, one-line solution.

Here is the "Pro Example" showing how easy it is to implement with zustand-sync-tabs:

// 1. Install: npm install zustand-sync-tabs zustand
import { create } from 'zustand';
import { syncTabs } from 'zustand-sync-tabs';

interface UserState {
  username: string;
  isLoggedIn: boolean;
  setUsername: (name: string) => void;
  setIsLoggedIn: (status: boolean) => void;
}

const useUserStore = create<UserState>()(
  // ✨ Simply wrap your store with syncTabs
  syncTabs(
    (set) => ({
      username: 'Guest',
      isLoggedIn: false,
      setUsername: (name) => set({ username: name }),
      setIsLoggedIn: (status) => set({ isLoggedIn: status }),
    }),
    {
      // 💡 Important: The unique name acts as the Broadcast Channel identifier
      name: 'user-auth-channel', 
      // Optional: Exclude certain fields from syncing (e.g., local UI state)
      exclude: ['isLoggedIn'],
    }
  )
);

// 🎉 Boom! Any change in Tab A's 'username' instantly updates Tab B.

By adding syncTabs (or a similar middleware), you ensure a seamless user experience, preventing the common headache of inconsistent data between windows. This is a must-have pattern for real-time dashboards, single sign-on flows, and multi-window productivity apps.

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