When building applications with React, managing state can quickly become a complex and time-consuming task. Luckily, there are many libraries available to help simplify this process. One of the most popular libraries for state management in React is MobX.
In this article, we will explore what MobX is, how it works, and how you can use it to manage state in your React applications.
What is MobX?
MobX is a simple, scalable, and efficient state management library for JavaScript applications. It provides a way to declaratively define the state of your application, and then automatically updates the user interface whenever that state changes.
MobX is inspired by reactive programming, which is a programming paradigm that focuses on how data changes over time. This makes MobX particularly well-suited for managing complex, data-driven applications.
MobX works by observing changes to your data and automatically updating any components that depend on that data. This makes it easy to keep your user interface in sync with your data, without having to write a lot of boilerplate code.
How Does MobX Work?
At its core, MobX is based on two concepts: observables and reactions.
Observables are simply objects that can be observed for changes. When an observable changes, MobX automatically triggers any reactions that depend on that observable.
Reactions are functions that are automatically re-executed whenever their dependencies change. This means that when an observable changes, any reactions that depend on it will automatically be re-executed.
Here is a simple example to illustrate how this works:
import { observable, autorun } from "mobx";
const state = observable({
count: 0,
});
autorun(() => {
console.log(state.count);
});
state.count = 1; // logs 1
state.count = 2; // logs 2
In this example, we define an observable called state, which has a property called count. We also define a reaction using the autorun function, which simply logs the value of state.count whenever it changes.
When we update state.count to 1, MobX automatically triggers the autorun function, which logs the new value of state.count. The same thing happens when we update state.count to 2.
This is a very simple example, but it illustrates the basic concepts behind MobX: observables and reactions.
How to Use MobX with React
Now that we understand the basic concepts behind MobX, let's see how we can use it with React.
Installing MobX
First, we need to install MobX and its related libraries. You can do this using npm or yarn:
npm install mobx mobx-react
# or
yarn add mobx mobx-react
Creating Observables
Next, we need to create some observables to represent the state of our application. We can do this using the observable function from MobX:
import { observable } from "mobx";
const store = observable({
count: 0,
increment() {
this.count++;
},
decrement() {
this.count--;
},
});
In this example, we define an observable called store, which has a property called count. We also define two functions called increment and decrement, which update the count property.
Using Observables in React Components
Once we have defined our observables, we can use them in our React components. To do this, we need to use the observer function from the mobx-react library:
import React from "react";
import { observer } from "mobx-react";
const Counter = observer(({ store }) => (
<div>
<h1>Count: {store.count}</h1>
<button onClick={() => store.increment()}>Increment</button>
<button onClick={() => store.decrement()}>Decrement</button>
</div>
));
In this example, we define a React component called Counter, which takes a store prop that represents our observable store. We use the observer function to wrap our component, which makes it automatically re-render whenever the observables it depends on change.
We can then use our Counter component like this:
import React from "react";
import ReactDOM from "react-dom";
import { observer } from "mobx-react";
import { observable } from "mobx";
const store = observable({
count: 0,
increment() {
this.count++;
},
decrement() {
this.count--;
},
});
const Counter = observer(({ store }) => (
<div>
<h1>Count: {store.count}</h1>
<button onClick={() => store.increment()}>Increment</button>
<button onClick={() => store.decrement()}>Decrement</button>
</div>
));
ReactDOM.render(<Counter store={store} />, document.getElementById("root"));
In this example, we create an instance of our observable store called store. We then render our Counter component and pass the store as a prop.
When we click the "Increment" or "Decrement" button, MobX automatically updates the count property of our store, which triggers a re-render of our Counter component.
Conclusion
MobX is a powerful library for managing state in React applications. It provides a simple and declarative way to define and update your application state, which can help reduce complexity and improve performance.
By using observables and reactions, MobX makes it easy to keep your user interface in sync with your data, without having to write a lot of boilerplate code.
In this article, we have covered the basics of using MobX with React, including how to install MobX, create observables, and use them in your React components. With this knowledge, you should be well on your way to building scalable and efficient React applications with MobX.