babel-upgrade

Usage

Run at the root of your git repo

npx babel-upgrade

Ideas from http://new.babeljs.io/docs/en/next/v7-migration.html (or modify that file if it's missing)

Todos

Update dependencies, config files, and maybe JavaScript files that require babel packages directly

• Works on Node >= 4 (anything lower isn't supported in v7)
• Update package.json: dependencies and devDependencies to the "latest supported" version.
  • all package renames
  • Upgrading the same package to the latest version
  • add @babel/core peerDep

{
  "devDependencies": {
+   "@babel/core": "7.0.0-beta.39",
+   "@babel/plugin-proposal-object-rest-spread": "7.0.0-beta.39",
+   "@babel/preset-env": "7.0.0-beta.39",
+   "babel-loader": "v8.0.0-beta.0"
-   "babel-loader": "6.0.0",
-   "babel-plugin-transform-object-rest-spread": "6.0.0",
-   "babel-preset-env": "^1.0.0",
  },
}

• modify scripts for mocha + @babel/register

{
  "name": "mocha-scripts-test",
  "scripts": {
-    "test": "mocha --compilers js:babel-register --require babel-polyfill test/*Test.js",
+    "test": "mocha --compilers js:@babel/register --require @babel/polyfill test/*Test.js",
  }
}

• use "babel-core": "^7.0.0-bridge-0" if jest is a dependency

"devDependencies": {
  "@babel/core": "7.0.0-beta.39",
+ "babel-core": "7.0.0-bridge.0",
  "jest": "^22.0.0"
},
"scripts": {
  "test": "jest"
}

• add new @babel/node package if babel-node is used

"devDependencies": {
  "@babel/cli": "7.0.0-beta.39",
+ "@babel/node": "7.0.0-beta.39"
},
"scripts": {
  "start": "babel-node a.js"
}

• if babel-node is used, import @babel/node?

{
  "devDependencies": {
+   "@babel/node": "7.0.0-beta.39"
  }
  "scripts": {
    "start": "babel-node"
  }
}

• Update the babel config file(s).
  • change all .babelrc files

- src/
- example/
  - .babelrc // now modifies these too
- test/
  - .babelrc // now modifies these too
- `.babelrc`

• rename config files to swap shorthand form to long form

{
  "presets": [
+   "@babel/preset-env"
-   "env"
  ]
}

• package.json babel key

{
  "babel": {
    "presets": [
+     "@babel/preset-env"
-     "env"
    ]
  }
}

• handle env

{
  "babel": {
    "presets": [
      "@babel/preset-env"
    ]
  },
  "env": {
    "development": {
      "plugins": [
-       "transform-react-jsx-source",
-       "babel-plugin-transform-react-jsx-self"
+       "@babel/plugin-transform-react-jsx-source",
+       "@babel/plugin-transform-react-jsx-self",
      ]
    }
  }
}

• Modify mocha.opts
• Log when replacing out preset-es2015,16,17,latest as FYI
• Auto run npm/yarn after updating dependencies
• figure out how to change nested .babelrcs into using "overrides" instead
• monorepo support
• .babelrc.js and other js files with a config like presets, webpack.config.js
• convert comma separated presets/plugins into an array
• handle react + flow preset being split. Read if .flowconfig and add it?
• convert only/ignore?
• how do we want to handle spec/loose modes, especially when changing previous loose mode to spec (just warn?)
• remove typeof-symbol if using @babel/preset-env + loose
• Update test files that use babel directly (babel-types -> @babel/types, babel-core)
  • Update all requires/imports
  • Update the use of the Babel API (plugins, integrations)
• Modify other config files as we go
• Add to the upgrade guide which parts are autofixable and the command (if we care enough to make this individually runnable too infrastructure wise)
• May need to add a warning on any 3rd party plugins since they might not be compatible
• Handle the differences in plugins in v7 for default/loose/spec
• Should certain parts be generic (replace the string babel-register with @babel/register)? Could be in a Makefile or somewhere else, but it's just find replace.

Philosophy

• Move this into the monorepo when somewhat ready
  • Maybe move into @babel/cli?
  • Or just another package that is intended to be used via npx/globally
• Whenever there is a breaking change in a PR we should also update this tool when possible or at least provide a warning
  • What about with a regression?
• Can be used for non-major bumps too - just for updating to the latest version.
• Include mini-changelog?
• Maybe the version should just reflect the version that it targets?

Development

$ npm i
$ npm start