Immutable State Management in JavaScript Applications
immer, immutability-helper, immutable, and seamless-immutable are libraries designed to help developers work with immutable data structures in JavaScript applications. Since JavaScript objects and arrays are mutable by default, these tools provide patterns or data types that enforce immutability—ensuring state changes create new references instead of modifying existing ones. This is especially valuable in UI frameworks like React, where predictable state updates improve performance and reduce bugs.
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Immutable State Management: immer vs immmutability-helper vs immutable vs seamless-immutable
Managing state without accidental mutations is a core challenge in modern frontend apps. These four libraries offer different strategies—from proxy-based mutation emulation to fully custom data structures. Let’s compare how they handle real-world scenarios.
🧪 Core Philosophy: How Each Library Enforces Immutability
immer uses JavaScript Proxies to let you "mutate" a draft state, then produces a new immutable snapshot.
- You write code as if you’re mutating an object.
- Under the hood, it tracks changes and builds a new object.
import { produce } from 'immer';
const nextState = produce(baseState, draft => {
draft.user.name = 'Alice'; // Looks like mutation
draft.posts.push({ id: 3, title: 'New Post' });
});
// nextState is a new object; baseState unchanged
immutability-helper uses command objects with special keys ($set, $push, etc.) to describe changes.
- No actual mutation occurs—you specify operations declaratively.
- Relies on string paths to target nested properties.
import update from 'immutability-helper';
const nextState = update(baseState, {
user: { name: { $set: 'Alice' } },
posts: { $push: [{ id: 3, title: 'New Post' }] }
});
immutable replaces native objects/arrays with its own classes (Map, List, etc.).
- All methods return new instances—mutation is impossible by design.
- Requires converting data to and from Immutable.js types.
import { Map, List } from 'immutable';
const baseState = Map({
user: Map({ name: 'Bob' }),
posts: List([{ id: 1, title: 'Old Post' }])
});
const nextState = baseState
.setIn(['user', 'name'], 'Alice')
.updateIn(['posts'], posts => posts.push(Map({ id: 3, title: 'New Post' })));
seamless-immutable extends plain JavaScript objects with non-mutating methods.
- Uses
Object.freeze()in development to catch mutations early. - Provides helpers like
setInthat return new objects.
import Immutable from 'seamless-immutable';
const baseState = Immutable({
user: { name: 'Bob' },
posts: [{ id: 1, title: 'Old Post' }]
});
const nextState = baseState
.setIn(['user', 'name'], 'Alice')
.updateIn(['posts'], posts => [...posts, { id: 3, title: 'New Post' }]);
🔌 Interoperability with Plain JavaScript Objects
immer: Works directly with standard JS objects/arrays. No conversion needed—input and output are plain data.
// Input and output are plain objects
const input = { count: 0 };
const output = produce(input, d => { d.count++ });
console.log(output instanceof Object); // true
immutability-helper: Also uses plain JS objects. Output matches input structure exactly.
const input = { count: 0 };
const output = update(input, { count: { $set: 1 } });
console.log(output instanceof Object); // true
immutable: Requires wrapping data in Immutable.js collections. To use with React or APIs, you must call .toJS().
const wrapped = Map({ count: 0 });
const plain = wrapped.toJS(); // { count: 0 }
seamless-immutable: Returns frozen plain objects. Can be used directly but may cause issues if downstream code tries to mutate them.
const state = Immutable({ count: 0 });
// state is a plain object, but frozen in dev mode
⚠️ Maintenance Status and Modern JavaScript Support
immer: Actively maintained, supports modern JS (including Symbols, Maps, Sets), and integrates well with Redux Toolkit.immutability-helper: Deprecated—last updated in 2017. Not recommended for new projects.immutable: Still maintained but in “long-term support” mode. The team recommends considering alternatives likeimmerfor new code.seamless-immutable: Unmaintained—last commit in 2020. Lacks support for newer language features.
🛠️ Nested Updates: Updating Deeply Structured Data
All libraries support updating nested paths, but syntax varies.
immer: Natural dot notation or bracket access.
produce(state, draft => {
draft.ui.sidebar.isOpen = false;
});
immutability-helper: Nested command objects with path segments.
update(state, {
ui: { sidebar: { isOpen: { $set: false } } }
});
immutable: setIn with array path.
state.setIn(['ui', 'sidebar', 'isOpen'], false);
seamless-immutable: setIn with array path.
state.setIn(['ui', 'sidebar', 'isOpen'], false);
📦 Performance Characteristics
immer: Efficient structural sharing. Only changed branches are copied. Uses Proxies, so minimal overhead in modern engines.immutability-helper: Creates full copies of intermediate objects along the path—can be inefficient for deep trees.immutable: Optimized persistent data structures (tries) enable fast reads/writes with minimal copying. But conversion cost (toJS()) can hurt performance.seamless-immutable: Always creates shallow copies up the path—no advanced sharing. Freezing in dev adds overhead.
🧩 Real-World Recommendation
For New React/Redux Projects
Use immer. It’s the de facto standard in modern Redux (via Redux Toolkit) and lets you write clean, readable code without boilerplate. Teams adopt it quickly because it feels like regular JavaScript.
For Legacy Codebases
- If you’re on
immutability-helper, migrate toimmer—the mental model shift is small. - If you’re on
seamless-immutable, evaluate migration effort;immeris the natural successor. - If you’re on
immutable, consider staying if you rely on its advanced collections—but for simple object trees,immerreduces friction.
When to Avoid Each
- Don’t start new projects with
immutability-helperorseamless-immutable—both are unmaintained. - Avoid
immutableif your app mostly deals with plain JSON-like data and you need seamless integration with external libraries. - Avoid
immeronly if you need compile-time guarantees (e.g., via TypeScript with branded types)—though even then,immerworks well with type guards.
✅ Summary Table
| Library | Data Type | Syntax Style | Maintained? | Interop with Plain JS |
|---|---|---|---|---|
immer | Plain objects | Mutable-looking | ✅ Yes | ✅ Excellent |
immutability-helper | Plain objects | Command objects | ❌ No | ✅ Good |
immutable | Custom classes | Method chaining | ⚠️ LTS only | ❌ Requires conversion |
seamless-immutable | Frozen objects | Helper methods | ❌ No | ⚠️ Limited (frozen) |
💡 Final Thought
Immutability isn’t just about correctness—it’s about making change detection efficient and debugging easier. Among active options, immer strikes the best balance: it hides complexity without sacrificing power, and it plays nicely with the rest of the JavaScript ecosystem. Unless you have specific needs for persistent data structures, it’s the pragmatic choice for most teams today.
How to Choose: immer vs immutability-helper vs immutable vs seamless-immutable
- immer:
Choose
immerif you want to write code that looks like mutable assignments but produces immutable updates under the hood. It’s ideal for teams already using plain JavaScript objects and arrays who need a low-friction way to adopt immutability without learning new APIs or changing data shapes. Itsproducefunction enables intuitive syntax while guaranteeing structural sharing and referential integrity. - immutability-helper:
Avoid
immutability-helperin new projects—it is deprecated and no longer maintained. Originally inspired by React’s oldupdate()helper, it uses string-based path commands (like$set,$push) to modify nested structures. While functional, its syntax is verbose and error-prone compared to modern alternatives. Use only if maintaining legacy code that already depends on it. - immutable:
Choose
immutablewhen you need guaranteed, deeply immutable data structures with rich APIs (e.g.,Map,List,Set) and built-in performance optimizations like hash maps and persistent tries. It enforces immutability at the type level, preventing accidental mutations. However, it requires wrapping and unwrapping data, which can complicate interoperability with libraries expecting plain JavaScript objects. - seamless-immutable:
Choose
seamless-immutableif you prefer working with plain JavaScript objects and arrays but want lightweight immutability enforcement. It freezes objects recursively in development and provides mutation-safe methods likesetInandmerge. However, it’s unmaintained as of 2023 and lacks support for modern JavaScript features. Only consider it for small projects or legacy systems where switching libraries isn’t feasible.
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README for immer
Immer
Create the next immutable state tree by simply modifying the current tree
Winner of the "Breakthrough of the year" React open source award and "Most impactful contribution" JavaScript open source award in 2019
Contribute using one-click online setup
You can use Gitpod (a free online VSCode like IDE) for contributing online. With a single click it will launch a workspace and automatically:
- clone the immer repo.
- install the dependencies.
- run
yarn run start.
so that you can start coding straight away.
Documentation
The documentation of this package is hosted at https://immerjs.github.io/immer/
Support
Did Immer make a difference to your project? Join the open collective at https://opencollective.com/immer!