React-MobX Error: The 'decorators' plugin requires a 'decoratorsBeforeExport' option, whose value must be a boolean

Question

I get the following error: If you are migrating from Babylon/Babel 6 or want to use the old decorators proposal, you should use the \'decorators-legacy\' plugin instead of \'dec

Answer 1

Answer are in the official document: https://mobx.js.org/best/decorators.html

you can find many ways to enable it in section "Enabling decorator syntax"

take the Babel 7 for example, create a project using mobx+create-react-app from scratch:

npx create-react-app hello-mobx

//This moves files around and makes your app’s configuration accessible.
npm run eject

npm install --save-dev babel-plugin-transform-decorators-legacy
npm install --save-dev @babel/plugin-proposal-decorators
npm install --save-dev @babel/plugin-proposal-class-properties

edit package.json: package.json:

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

install mobx:

npm install mobx --save
npm install mobx-react --save

enjoy!