Immer is a popular library in the JavaScript ecosystem that enables immutable data updates in a more convenient and declarative way. It provides a simple API for working with immutable data structures, making it easier to handle state management in complex applications.

Installation

To get started with Immer, you first need to install it as a dependency in your project. Open your terminal and run the following command:

npm install immer

Basic Usage

Once Immer is installed, you can import it into your project using the import statement.

import produce from "immer";

The produce function is the main API that Immer provides. It takes two arguments: a base state and a modifier function. The modifier function receives a draft state that you can safely mutate, and any changes made to the draft will be automatically applied to the base state.

Here’s an example of how to use Immer to update an object state:

const state = {
  name: "John",
  age: 30
};

const nextState = produce(state, (draft) => {
  draft.age += 1;
});

console.log(nextState);

In the code above, we start with a state object containing a name and age property. We then use the produce function to create a nextState by applying changes to the draft state. In this case, we increment the age property by 1.

When running the code, we expect the console.log statement to output the updated state:

{ name: "John", age: 31 }

Immer Proxies and Syntax

Immer internally uses ES6 Proxies to track changes made to the draft state. This enables a syntax that is very similar to working with mutable state. You can read and write properties on the draft state as if it were a normal mutable object.

For example:

const nextState = produce(state, (draft) => {
  draft.age += 1;
  draft.name = "Jane";
});

In the code above, we increment the age property by 1 and simultaneously change the name property to “Jane”. The changes made inside the modifier function are automatically applied to the draft state.

Additionally, Immer provides a “curried” version of the produce function, which allows you to create a partially applied producer function for later use. This can be helpful in cases where you want to reuse the same modifier function across different states.

const incrementAge = produce((draft) => {
  draft.age += 1;
});

const nextState = incrementAge(state);

In the code above, we create an incrementAge function using produce. This will return a partially applied producer function that increments the age property. We can then apply this function to different states to get the desired outcome.

Conclusion

In this article, we covered the basics of getting started with Immer. We explored its installation process, basic usage, and syntax. Immer simplifies and improves the way we work with immutable data in JavaScript, providing cleaner and more concise code for state management. Start using Immer today to enhance your application’s state management capabilities.

#hashtags: #Immer #JavaScript