create-react-app — how to set EXTEND_ESLINT to true?
Solution 1
In the project root directory, you can create the .env
file with EXTEND_ESLINT
set to true
so as to extend the ESLint config:
EXTEND_ESLINT=true
Also this also works:
EXTEND_ESLINT = "true"
Tried with create-react-app version 3.4.1, the latest version at the time of writing.
As an example, you can override the no-unused-vars
rule in the package.json
, as below:
...
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject",
"lint": "eslint src"
},
"eslintConfig": {
"extends": ["react-app"],
"rules": {
"no-unused-vars": "off"
}
},
...
Now run the linter, e.g., npm run lint
, you will not see any warning even if you have assigned a value to a variable but never used it in your application, kind of warning which you would normally see by the default settings. For example:
const App = () => {
let myVar = 1; // Never used
...
}
Note: npm start
and npm run build
, etc., will also honour the extended rules.
By the way, the original package.json
looks like this:
...
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"eslintConfig": {
"extends": "react-app"
},
...
Note: Another way to configure ESLint is to remove the eslintConfig
entry from the package.json
file and create .eslintrc
or .eslintrc.json
in the project root directory as below:
{
"extends": ["react-app"],
"rules": {
"no-unused-vars": "off"
}
}
[Update] If you find that react-scripts is not honouring your change to the ESLint rules, it is most likely caused by the cache. It is an open issue of the project at the moment. You can manually disable the cache in node_modules/react-scripts/config/webpack.config.js
like below:
use: [
{
options: {
cache: true, // You can set it to false
formatter: require.resolve('react-dev-utils/eslintFormatter'),
eslintPath: require.resolve('eslint'),
resolvePluginsRelativeTo: __dirname,
// @remove-on-eject-begin
ignore: isExtendingEslintConfig,
baseConfig: isExtendingEslintConfig
? undefined
: {
extends: [require.resolve('eslint-config-react-app')],
},
useEslintrc: isExtendingEslintConfig,
// @remove-on-eject-end
},
Note that this workaround would only be for your local development. You don't need to do anything for your build pipeline most likely, as the pipeline usually builds from scratch; so there is no such cache issue out there.
Solution 2
After struggling for hours, thanks to @Yuci my eslint is finally understanding my configurations.
Instead of directly fixing the package file in node_modules/react-scripts/config/webpack.config.js
, I have added npm scripts to always bust out the cache in start of npm run start
and npm run build
.
This way you don't have to fear for 'accidentally' rebuilding the package in the future by rm -rf node_modules; npm install
-- future me is not that clever.
in packages.json
, change the scripts entity like the following:
"scripts": {
"start": "npm run clear_cache:eslint && react-scripts start",
"build": "npm run clear_cache:eslint && react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject",
"clear_cache:eslint": "rm -rf node_modules/.cache/eslint-loader"
},
Kirk Ross
I'm a singer/songwriter and web designer living in Pasadena, CA. Ironic trivia: my brother plays Gavin Belson on Silicon Valley.
Updated on July 27, 2022Comments
-
Kirk Ross almost 2 years
I have created a
.env
file in my project root but I'm new to working with environments / variables and so I'm unsure how to integrate the file so I can override the stock, non-ejected react-app eslint settings.// My .env file has just this EXTEND_ESLINT = "true"
The c-r-a docs explain what the variable is, but not now to set it to true. Also, the section on 'Extending the ESLint config' is helpful only for once the var is set to true.
// stock create-react-app package.json "scripts": { "start": "react-scripts start", "build": "react-scripts build", "test": "react-scripts test", "eject": "react-scripts eject" },
-
EnZo almost 4 yearsThis does not work. When I run the
npm run eslint
command it works. But when I runnpm run dev
the errors still show up. -
Yuci almost 4 years@EnZo thanks for the comments. See the note in my updated answer, and it should work for
npm run dev
in your setup with environment variable EXTEND_ESLINT set to true. -
EnZo almost 4 yearsStill not working, I have the exact same configuration in the
EXTEND_ESLINT=true
line in my.env
. And also the{ "extends": ["react-app"], "rules": { "no-unused-vars": "off" } }
in thepackage.json
. Tried also as.eslintrc
or.eslintrc.json
-
Yuci almost 4 yearsWhich create-react-app version do you use? @EnZo or more info about your react version, react-scripts version, etc.?
-
Yuci almost 4 years@EnZo, it's about eslint cache, see my reply: github.com/facebook/create-react-app/issues/9007
-
EnZo almost 4 yearsI just had to upgrade
"react-scripts": "3.4.1"
. Thank you @Yuci. -
Codebling over 3 yearsPlease take my upvote. I was skeptical, but setting
cache: false
fixed it for me. Thank you -
fadehelix over 3 years@Yuci your advice about
cache
flag in thenode_modules/react-scripts/config/webpack.config.js
solved my weird problems with custom config :D Thank you so much! -
Brian McCall over 3 yearsThank you! It was the cache thing for me also. I was stuck on this for days!