In web development, managing state is a crucial aspect of building robust applications. One challenge developers face is how to persist and restore state when the user navigates away or refreshes the page. Immer, a popular library for immutable state management, provides a convenient solution to this problem.

What is Immer?

Immer is a JavaScript library that simplifies working with immutable state by creating a draft state that can be modified and then produces an updated immutable state. It provides a simple and intuitive API that makes state management much easier.

State Persistence with Immer

To persist state with Immer, we can leverage browser storage mechanisms like localStorage or sessionStorage. By saving the immutable state serialized as JSON, we can restore and load it whenever necessary.

Here’s an example of persisting and restoring state using Immer and localStorage:

import { produce } from 'immer';

const initialState = {
  count: 0,
};

// Helper function to persist state
const persistState = (state) => {
  localStorage.setItem('appState', JSON.stringify(state));
};

// Helper function to restore state
const restoreState = () => {
  const savedState = localStorage.getItem('appState');
  return savedState ? JSON.parse(savedState) : initialState;
};

// Create a "draft" of the state and modify it using Immer
const newState = produce(restoreState(), (draftState) => {
  draftState.count += 1;
});

// Persist the updated state
persistState(newState);

console.log(newState); // Output: { count: 1 }

In the example above, we start by defining an initialState object. We then create helper functions, persistState and restoreState, which handle the serialization and deserialization of the state using localStorage.

Finally, we create a new state using produce and modify it within the Immer draft function. After updating the state, we persist the modified state using persistState.

By following this pattern, we can easily handle state persistence with Immer and ensure that our application’s state is preserved across page reloads or when the user navigates away.

Conclusion

Immer is a powerful library that simplifies state management in JavaScript applications. By leveraging Immer’s draft/state pattern along with browser storage mechanisms like localStorage, we can handle state persistence and ensure a seamless user experience. With Immer’s intuitive API and immutability features, handling state becomes more manageable and less error-prone.

#immutable #statepersistence