mobx + react unexpected token

Question

so i created an app with react without configuration from https://facebook.github.io/react/blog/2016/07/22/create-apps-with-no-configuration.html

I installed mobx and mobx-react ,but is still shows the error of unexpected token before @ symb.

Do I need to add something else, or my current configuration is wrong ?:(

package.json

"devDependencies": {
"react-scripts": "0.8.4",
"babel-core": "^6.7.6",
"babel-loader": "^6.2.4",
"babel-preset-es2015": "^6.6.0",
"babel-preset-react": "^6.5.0",
"babel-preset-stage-0": "^6.5.0"
},
"dependencies": {
"autobind-decorator": "^1.3.4",
"classnames": "^2.2.5",
"lodash": "^4.15.0",
"mobx": "^2.5.1",
"mobx-react": "^3.5.5",
"react": "^15.3.1",
"react-dom": "^15.3.1",
"validator": "^5.6.0"
 },

.babelrc

{
  "presets": ["es2015", "stage-0", "react"],
  "plugins": [
      "transform-decorators-legacy",
      "transform-class-properties"
  ]
}

And the code

import React, { Component } from 'react';
import { action, observable } from 'mobx'
import {observer} from 'mobx-react';


class App {
    @observer cake = [];
}

export default new App();

Answer 1

create-react-app does not support decorators (@). You could either eject create-react-app to add it yourself, set up your own environment from scratch, or use something like mobx-react-boilerplate as your starting point.

I have personally used react-app-rewired with the mobx extension with great success.

Answer 2

You could use the syntax provided that doesn't use decorators (here and here).

Here's an example using the App class code you provided:

import React, { Component } from 'react';
import { action, extendObservable } from 'mobx'
import {observer} from 'mobx-react';


class App {
  constructor() {
    extendObservable(this, {
      cake = [],
    }); 
  }
}

export default new App();

Answer 3

You are missing packages after running npm run eject (as create-react-app does not support decorators).

Run npm install --save-dev babel-plugin-transform-decorators-legacy babel-plugin-transform-class-properties

Then add the following Babel configuration to your package.json

"babel": {
  "plugins": [
    "transform-decorators-legacy"
  ],
  "presets": [
    "react-app"
  ]
},