@ljharb Are there any other steps I should take to get this merge-ready?

@christianbundy Awesome! Can we add ctx for koa routing as well? Other than that, we're good to go :-)

Done! Let me know if you'd like to squash my commits before the merge, thanks for working with me on this PR.

@christianbundy yes, please do rebase it down to one commit :-) please also prefix the commit message with [eslint config] [base] . Thanks!

Weird, this page started throwing HTTP 500 errors after I force-pushed, and it looks like it auto-closed? Anyway, I re-opened it with the new commit message, please let me know if there's anything else.

After this changes, I'm getting this error:

Failed to compile.
Error in ./src/actions/actions.js
Module build failed: Error: \node_modules\eslint-config-airbnb-base\rules\best-practices.js:
Configuration for rule "no-param-reassign" is invalid:
Value "data["0"].ignorePropertyModificationsFor" has additional properties.
Referenced from: \node_modules\eslint-config-airbnb-base\index.js
Referenced from: airbnb
Referenced from: .eslintrc.js
at Array.forEach (native)
at Array.reduceRight (native)
at Array.reduceRight (native)
at Array.reduceRight (native)

I have these versions in my package.json:

"eslint": "3.15.0",
"eslint-config-airbnb": "^14.1.0",
"eslint-config-react-app": "^0.5.2",
"eslint-loader": "1.6.0",
"eslint-plugin-flowtype": "2.21.0",
"eslint-plugin-import": "2.2.0",
"eslint-plugin-jsx-a11y": "^4.0.0",
"eslint-plugin-react": "6.9.0",

If I change back to the oldest version, everything works properly. Do you have any suggestions about it?

Hey @coldfish, do you get any errors when you run npm install? You should be getting a warning for that ESLint package, since ESLint v3.18.0 is listed as a peer dependency. This functionality was released in ESLint v3.17.0, would it be possible to upgrade to the most recent version of ESLint?

After npm install, I only got this WARN message:

npm WARN eslint-config-react-app@0.5.2 requires a peer of eslint-plugin-jsx-a11y@^2.2.3 but none was installed.

Based on the installation documentation (https://github.com/airbnb/javascript/tree/master/packages/eslint-config-airbnb), I have installed these versions after getting the output of "npm info "eslint-config-airbnb@latest" peerDependencies":

{ eslint: '^3.15.0',
  'eslint-plugin-jsx-a11y': '^3.0.2 || ^4.0.0',
  'eslint-plugin-import': '^2.2.0',
  'eslint-plugin-react': '^6.9.0' }

So I thought they're the right dependencies to proceed. Should we have update the documentation for this problem?

Thanks for your quick reply.

It looks like you're right, that eslint-config-airbnb package has a minimum peer dependency of ESLINT v3.16.1, but if you want to use ESLint's newer features you'll need to upgrade to a more recent version of ESLint. I'm not on the Airbnb team, but I assume this is similar to how you wouldn't be able to use ES6-specific styles unless your JS engine was capable.

The peerDependency you mentioned above is ^3.15.0, which is equivalent to 3.x.x. It looks like you may have accidentally locked the specific versions rather than used the caret, can you try this?

npm install --save-dev eslint@^3.15.0 eslint-plugin-jsx-a11y@^4.0.0 eslint-plugin-import@^2.2.0 eslint-plugin-react@^6.9.0

Thanks @christianbundy. This answer is pretty enough for me. As you said, most probably, I've made a mistake while installing the packages related to caret.

After updating the version to 3.18.0, the error has gone.

Also note, when updating eslint-config-airbnb or eslint-config-airbnb-base, please always use the install command in the package readme, so the peer dep versions end up correct.