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0

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'React' was used before it was defined

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.
12 months ago · Santiago Trujillo
17 answers
Answer question

0

I got this error from the airbnb-base ruleset in a typescript project. Also extending airbnb-typescript (that has the correct rules for typescript) resolved the issue.

12 months ago · Santiago Trujillo Report

0

This has been resolved in 4.4.0. Upgrade these dependencies to version 4.4.0

Update: This may work for some use cases. This resolved my issue.

"@typescript-eslint/eslint-plugin": "^4.4.0",
"@typescript-eslint/parser": "^4.4.0",
   
12 months ago · Santiago Trujillo Report

0

My fix for that: Use eslint 6 as react-scripts is using Force react scripts to use newer @typescript-eslint packages as the rest of the repo. I'm using selective resolution here

  "resolutions": {
    "**/react-scripts/**/@typescript-eslint/eslint-plugin": "^4.4.1",
    "**/react-scripts/**/@typescript-eslint/parser": "^4.4.1"
  }

@typescript-eslint 4.x does still support es6

12 months ago · Santiago Trujillo Report

0

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"
}
12 months ago · Santiago Trujillo Report

0

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"
  ],
}
12 months ago · Santiago Trujillo Report

0

Try adding import/resolver to your Eslint settings:

  "settings": {
    "react": { "version": "detect" },
    "import/resolver": { "typescript": {} }
  }

Maybe you will need to install it too:

$ yarn add -D eslint-import-resolver-typescript

If that doesn't work, you could change this rule

"@typescript-eslint/no-use-before-define": "off"

like this:

"no-use-before-define": "off"
12 months ago · Santiago Trujillo Report

0

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'),
  1. Add ENV varialbe to .env file. More info
 EXTEND_ESLINT=true
  1. 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"
},
12 months ago · Santiago Trujillo Report

0

It is an issue present in ESLINT.

The way I resolve is to add the following lines to the ESLINT/rules:

"no-use-before-define": [0],
"@ typescript-eslint / no-use-before-define": [1],

12 months ago · Santiago Trujillo Report

0

I deleted packages @typescript-eslint/eslint-plugin and @typescript-eslint/parser from my package.json, deleted node_modules and package-lock.json, reinstalled packages: npm install The error disappeared.

UPDATE

After that create-react-app uses their own @typescript-eslint/eslint-plugin module which is deprecated.

12 months ago · Santiago Trujillo Report

0

I just wanted to add that for me, I did the following.

  1. Removed all eslint related dependencies from package.json if they were already included in package-lock.json by react-scripts (for me that was all of them)
  2. Deleted my node_modules folder, and package-lock.json file
  3. Ran npm install

After completing those steps I finally got that error to go away. I prefer removing the dependencies to downgrading them since this will help avoid the same issue happening again in the future.

12 months ago · Santiago Trujillo Report

0

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

react-scripts@4.0.0 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.

12 months ago · Santiago Trujillo Report

0

(not enough rep to comment)

@sashko's workaround seems to work - deleting node_modules was necessary as well.

One thing I missed was the caret in "^4.0.1". The version needs to be fixed without the caret ^, which seems to be the issue that @Rolly is having. Make sure it's 4.0.1.

Only a workaround until react-scripts updates to v4 (I'm using create-react-app)

12 months ago · Santiago Trujillo Report

0

deleting the node_modules folder and reinstalling it worked for me. I'm using yarn as package manager.

12 months ago · Santiago Trujillo Report

0

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"]
}
12 months ago · Santiago Trujillo Report

0

Try using Yarn instead of NPM (make sure to remove your node_modules in between).

This worked for me.

12 months ago · Santiago Trujillo Report

0

I know that this post does not solve the issue directly, but you can bypass this issue if you stick to best practices regarding imports. Try to import exactly what you want, and you will get rid of this error also. For example:

import { useState, useEffect } from React;
// and then continue with your code
12 months ago · Santiago Trujillo Report

0

If you use Create React App. Getting the latest version of react-scripts fixed this issue for me. Currently: 4.0.3

// Get this specific version:
npm uninstall react-scripts
npm install react-scripts@4.0.3

// Get latest version:
npm uninstall react-scripts
npm install react-scripts
12 months ago · Santiago Trujillo Report
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