mobx-state-tree is a state management library that combines the simplicity and ease of MobX with a powerful model system. It allows developers to create complex, structured state trees with built-in support for snapshots, patches, and much more. While mobx-state-tree offers a robust solution for state management, there are other libraries in the React ecosystem that provide alternative approaches. Here are a few alternatives:

• immer is a library that simplifies the process of working with immutable data in JavaScript. It allows developers to write simpler, more readable code when updating immutable data structures.
• mobx is a reactive state management library that enables developers to create observable state and automatically track and update dependencies. It provides a simple and efficient way to manage state in React applications.
• recoil is a state management library for React applications that focuses on providing a minimal API surface while offering advanced capabilities like atom effects and selectors.
• redux is a predictable state container for JavaScript applications. It provides a centralized store for managing application state and enables developers to write consistent, testable code.

Check out this comparison: Comparing immer vs mobx vs mobx-state-tree vs recoil vs redux.

mobx-state-tree

What is mobx-state-tree?

Technically speaking, mobx-state-tree (also known as MST) is a state container system built on MobX, a functional reactive state library.

This may not mean much to you, and that’s okay. I’ll explain it like this: MobX is a state management "engine", and MobX-State-Tree gives it structure and common tools you need for your app. MST is valuable in a large team but also useful in smaller applications when you expect your code to scale rapidly. And if we compare it to Redux, MST offers better performance and much less boilerplate code than Redux!

MobX is one of the most popular Redux alternatives and is used (along with MobX-State-Tree) by companies worldwide. MST plays very well with TypeScript, React, and React Native, especially when paired with mobx-react-lite. It supports multiple stores, async actions and side effects, enables extremely targeted re-renders for React apps, and much more -- all in a package with zero dependencies other than MobX itself.

Note: you don't need to know how to use MobX in order to use MST.

Getting started

See the Getting started tutorial or follow the free egghead.io course.

👉 Official docs can be found at http://mobx-state-tree.js.org/

Quick Code Example

There's nothing quite like looking at some code to get a feel for a library. Check out this small example of an author and list of tweets by that author.

import { types } from "mobx-state-tree" // alternatively: import { t } from "mobx-state-tree"

// Define a couple models
const Author = types.model({
  id: types.identifier,
  firstName: types.string,
  lastName: types.string
})
const Tweet = types.model({
  id: types.identifier,
  author: types.reference(Author), // stores just the `id` reference!
  body: types.string,
  timestamp: types.number
})

// Define a store just like a model
const RootStore = types.model({
  authors: types.array(Author),
  tweets: types.array(Tweet)
})

// Instantiate a couple model instances
const jamon = Author.create({
  id: "jamon",
  firstName: "Jamon",
  lastName: "Holmgren"
})

const tweet = Tweet.create({
  id: "1",
  author: jamon.id, // just the ID needed here
  body: "Hello world!",
  timestamp: Date.now()
})

// Now instantiate the store!
const rootStore = RootStore.create({
  authors: [jamon],
  tweets: [tweet]
})

// Ready to use in a React component, if that's your target.
import { observer } from "mobx-react-lite"
const MyComponent = observer((props) => {
  return <div>Hello, {rootStore.authors[0].firstName}!</div>
})

// Note: since this component is "observed", any changes to rootStore.authors[0].firstName
// will result in a re-render! If you're not using React, you can also "listen" to changes
// using `onSnapshot`: https://mobx-state-tree.js.org/concepts/snapshots

Thanks!

• Michel Weststrate for creating MobX, MobX-State-Tree, and MobX-React.
• Infinite Red for supporting ongoing maintenance on MST.
• Mendix for sponsoring and providing the opportunity to work on exploratory projects like MST.
• Dan Abramov's work on Redux has strongly influenced the idea of snapshots and transactional actions in MST.
• Giulio Canti's work on tcomb and type systems in general has strongly influenced the type system of MST.
• All the early adopters encouraging to pursue this whole idea and proving it is something feasible.