'React' was used before it was defined

Question

I am working with create-react-app + typescript + eslint application and during build have such error:

Line 1:8:  'React' was used before it was defined  @typescript-eslint/no-use-before-define

Code in my component starts with:

import React from "react";

Eslint settings:

module.exports = {
  parser: "@typescript-eslint/parser",
  parserOptions: {
    ecmaVersion: 2020,
    sourceType: "module",
    ecmaFeatures: {
      jsx: true
    }
  },
  settings: {
    react: {
      version: "detect"
    }
  },
  extends: [
    "plugin:react/recommended",
    "plugin:@typescript-eslint/recommended",
    "prettier/@typescript-eslint",
    "plugin:prettier/recommended"
  ],
  rules: {
    "@typescript-eslint/explicit-module-boundary-types": 0,
    "@typescript-eslint/triple-slash-reference": 0,
    "no-use-before-define": "off",
    "@typescript-eslint/no-use-before-define": "off"
  },
};

Some part of package.json:

"devDependencies": {
  "@typescript-eslint/eslint-plugin": "^4.1.0",
  "@typescript-eslint/parser": "^4.1.0",
  "babel-eslint": "^10.1.0",
  "eslint": "^6.6.0",
  "eslint-config-airbnb": "^18.1.0",
  "eslint-config-prettier": "^6.11.0",
  "eslint-plugin-import": "^2.20.2",
  "eslint-plugin-prettier": "^3.1.3",
  "eslint-plugin-react": "^7.20.0",
  "prettier": "^2.0.5",
  "start-server-and-test": "^1.11.3"
},
"dependencies": {
  ...
  "react-scripts": "3.4.3",
  ...
}

I tried:

• Read https://github.com/typescript-eslint/typescript-eslint/issues/2502
• Disable @typescript-eslint/no-use-before-define and no-use-before-define in .eslintrc.js
• Actually I tried to delete .eslintrc.js at all, but had the same error.

Solution 1

The bug occurs due to mismatch of @typescript-eslint versions in react-scripts and your local package.json - GitHub issue

You can downgrade the packages until react-scripts updates their version.

    "@typescript-eslint/eslint-plugin": "4.0.1",
    "@typescript-eslint/parser": "4.0.1",

EDIT 2020-09-14

It seems the bug is not related to react-scripts version of @typescript-eslint since multiple people reported the same bug without using react-scripts.

Anyway, the workaround remains the same - downgrade to the working version of @typescript-eslint until the fix is available.

EDIT 2020-10-24

[email protected] has been published with updated @typescript-eslint. Using the newest version should solve the issue.

EDIT 2020-11-04

If after upgrading the packages the error is still there, most probably your eslint config uses the wrong rule. Check out Igor's answer to fix it.

Solution 2

From the official documentation.

"rules": {
  // note you must disable the base rule as it can report incorrect errors
  "no-use-before-define": "off",
  "@typescript-eslint/no-use-before-define": ["error"]
}

Solution 3

If you are only getting this error for .js files, make sure @typescript-eslint/parser is being used exclusively on Typescript files.

.eslintrc.json (abbreviated)

{
  "overrides": [
    {
      "files": ["**/*.ts", "**/*.tsx"],
      "plugins": ["@typescript-eslint"],
      "rules": {
        "no-use-before-define": "off",
        "@typescript-eslint/no-use-before-define": ["error"],
      },
    }
  ],
  // WRONG: Do not use @typescript-eslint/parser on JS files
  // "parser": "@typescript-eslint/parser",
  "plugins": [
    "react",
    // "@typescript-eslint"
  ],
}

Solution 4

That is how I resolved my problem.

1. First of all, go to the node_modules/react-scripts/config/webpack.config.js and change cache to false, because this will help you to understand what works and what is not then you changing eslint file. I found it here

 cache: true, // You can set it to false
 formatter: require.resolve('react-dev-utils/eslintFormatter'),

2. Add ENV varialbe to .env file. More info

 EXTEND_ESLINT=true

3. From now CRA will have to use your local eslint for linting during your build and we have control to disable some rules, in my case in .eslintrc:

rules: {
    "@typescript-eslint/no-use-before-define": "off"
},

Solution 5

I landed on this page after I started getting issues with a Gatsby project that was using Typescript and an ESLint config that extended eslint-config-airbnb-typescript. In addition to OP's error, ESLint was also giving errors on various rules not being defined, like Definition for rule '@typescript-eslint/no-redeclare' was not found. and a few others.

The underlying problem ended up being that Gatsby was using fairly old versions of both @typescript-eslint/eslint-plugin and @typescript-eslint/parser. Forcing yarn to install only up-to-date versions solved the issue:

// package.json
"resolutions": {
    "@typescript-eslint/eslint-plugin": "^4.4.0",
    "@typescript-eslint/parser": "^4.4.0"
}

View more solutions

Comments

[Rolly]

did not worked for me. "react": "^16.13.1", "typescript": "~3.7.2", "@typescript-eslint/eslint-plugin": "^4.0.1", "@typescript-eslint/parser": "^4.0.1". Same error as the post.

[sashko]

Have you tried deleting node_modules and reinstalling the packages?

[Rolly]

i did but the warning keeps there.

[sashko]

In your package.json specify typescript-eslint version without caret ^ as it will install the latest minor version, not 4.0.1.

[pho3nixf1re]

Upgrading react-scripts to v4.0.0 (next as of this writing) fixes this. npm i react-scripts@next.

[Ben Gotow]

Can confirm that using react-scripts@next and the latest typescript-eslint deps resolves the issue

[Mufasa]

This was the only thing that worked for me - thanks!

[xdemocle]

it's not. I tested 4.4.0 and 4.4.1

[feihcsim]

for me, it wasn't just react-scripts that kept an outdated version of @typescript-eslint as a dependency. i found out the other culprits with yarn list @typescript-eslint/eslint-plugin @typescript-eslint/parser

[Jose A]

Careful on modifying it directly as it'd get overwritten by a yarn/npm install. I'd recommend to do the webpack.config.js modification through craco: github.com/gsoft-inc/craco

[jtschoonhoven]

See also this recommendation from a maintainer of typescript-eslint github.com/typescript-eslint/typescript-eslint/issues/…

[Rahul Gandhi]

It worked for me only after downgrading to the versions specified ( without caret obviously)

[j0hnm4r5]

This worked for me when I set these within "resolutions" inside my package.json.

[Domagoj Vuković]

This saved me thanks. After doing some digging it seems like gatsby installs both of those libs with ^2.24.0 version which is super old and they get used for some reason. So frustrating that on the docs it says, just make your own .eslintrc and all good, and then they include their own parser and ruleset that gets used.

[Little Brain]

I had to put this in overrides: "parser": "@typescript-eslint/parser", "plugins": ["@typescript-eslint/eslint-plugin"],

[codenamezero]

Doesn't work. I am using @typescript-eslint 4.22.

[Praym]

The rules settings as mentioned above, worked for me. Turn off the first rule which is buggy and turn on the second which is works fine.

[Ian]

Adding just "no-use-before-define": "off", to my .eslintrc.json rules did it for me.

[igor]

@Praym first rule is not buggy. Original ESLint rules are valid for JS only even though many work with TS with no issues. You should switch off JS rule before using a matching TS rule. github.com/typescript-eslint/typescript-eslint/blob/main/…

[Sacru2red]

check "@typescript-eslint/eslint-plugin" at yarn.lock or package-lock.json, if other lib uses other version, sync your version