# MobX example

Usually splitting your app state into `pages` feels natural but sometimes you'll want to have global state for your app. This is an example on how you can use mobx that also works with our universal rendering approach. This is just a way you can do it but it's not the only one.

In this example we are going to display a digital clock that updates every second. The first render is happening in the server and then the browser will take over. To illustrate this, the server rendered clock will have a different background color than the client one.

![](http://i.imgur.com/JCxtWSj.gif)

The clock, under `components/Clock.js`, has access to the state using the `inject` and `observer` functions from `mobx-react`. In this case Clock is a direct child from the page but it could be deep down the render tree.

This example is a mobx port of the [with-redux](https://github.com/zeit/next.js/tree/master/examples/with-redux) example. Decorator support is activated by adding a `.babelrc` file at the root of the project:

```json
{
  "presets": ["next/babel"],
  "plugins": [
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    ["@babel/plugin-proposal-class-properties", { "loose": true }]
  ]
}
```

## Deploy your own

Deploy the example using [ZEIT Now](https://zeit.co/now):

[![Deploy with ZEIT Now](https://zeit.co/button)](https://zeit.co/import/project?template=https://github.com/zeit/next.js/tree/canary/examples/with-mobx)

## How to use

### Using `create-next-app`

Execute [`create-next-app`](https://github.com/zeit/next.js/tree/canary/packages/create-next-app) with [npm](https://docs.npmjs.com/cli/init) or [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/) to bootstrap the example:

```bash
npm init next-app --example with-mobx with-mobx-app
# or
yarn create next-app --example with-mobx with-mobx-app
```

### Download manually

Download the example:

```bash
curl https://codeload.github.com/zeit/next.js/tar.gz/canary | tar -xz --strip=2 next.js-canary/examples/with-mobx
cd with-mobx
```

Install it and run:

```bash
npm install
npm run dev
# or
yarn
yarn dev
```

Deploy it to the cloud with [ZEIT Now](https://zeit.co/import?filter=next.js&utm_source=github&utm_medium=readme&utm_campaign=next-example) ([Documentation](https://nextjs.org/docs/deployment)).

### Rehydrating with server data

Be aware that data that was used on the server (and provided via one of Next.js data fetching methods) will be stringified in order to rehydrate the client with it. That means, if you create a store that is, say, an `ObservableMap` and give it as prop to a page, then the server will render appropriately. But stringifying it for the client will turn the `ObservableMap` to an ordinary JavaScript object (which does not have `Map`-style methods and is not an observable). So it is better to create the store as a normal object and turn it into a `Observable` in the `render()` method. This way both sides have an `Observable` to work with.