ESLint - 'process' is not defined

Question

I am using ESLinter for a simple node project. Below is the only code I have in index.js:

const express = require('express');
const app = express();

app.get('/', (req, res) => {
    res.send({
        hi: 'there'
    });
});

const PORT = process.env.PORT || 5000;
app.listen(PORT);

I am using VSCode editor. It automatically runs ESLint for JS code.

In the IDE, I see below error for last but one line -

[eslint] 'process' is not defined. (no-undef)

Any Idea what's wrong?

Fall

does ESLINT have some way of informing it you are linting nodejs code? – Europe

You probably haven't configured eslint correctly. eslint.org/docs/user-guide/configuring#specifying-environments – Czardas

Thanks @FelixKling - It was so dumb of me not looking into .eslintrc.json file. I had accidentally selected browser default global variables. Your link hinted me to that. Now, the error is gone! – Fall

Answer 1

When I got error I had "browser": true instead of "node": true.

I have fixed this with following config for .eslintrc.json file-

{
    "env": {
        "node": true,
        "commonjs": true
    },
    "extends": "eslint:recommended",
    "rules": {
        "indent": [
            "error",
            "tab"
        ],
        "linebreak-style": [
            "error",
            "unix"
        ],
        "quotes": [
            "error",
            "single"
        ],
        "semi": [
            "error",
            "always"
        ]
    },
    "parserOptions": {
        "ecmaVersion": 2015
    }
}

Thanks @FelixKling and @Jaromanda X for quick responses.

Fall

This got rid of my ESlint 'URL' is not defined, too. – Ingar

In my case I was missing the node: true on my env eslint config file. – Lovettalovich

Adding the "node" : true worked for me also with this issue. – Golda

Thought I selected "node" in the wizard at npm init @eslint/config but seems I didn't heh – Altercation

Answer 2

Adding "node": "true" to an existing list of environments will do the job, too

"env": {
        "node": true,
        "commonjs": true,
        "browser": true,
        "es6": true
       }

Gaither

Answer 3

Add .eslintrc file to root of your project (if you don't already have one) and define globals to ignore

{
    "globals": {
        "process": true
      }
}

Make sure you use process.env though out the project but only in a single configuration file. Consider adding no-process-envrule.

https://eslint.org/docs/rules/no-process-env

Dipper

This is useful if you're using a bundler like Parcel, which exposes process in a browser context. – Walkin

This is the correct way if your're implementing a frontend application. – Carbolated

Answer 4

If you have eslint installed, add env: { node: true } to the .eslintrc.js file

Photomicroscope

Answer 5

This config helped me and can help others too.

{
  "parser": "babel-eslint",
  "parserOptions": {
    "ecmaFeatures": {
      "jsx": true,
      "modules": true
    },
    "ecmaVersion": 2020,
    "sourceType": "module",
    "useJSXTextNode": true,
    "warnOnUnsupportedTypeScriptVersion": false
  },
  "root": true,
  "env": {
    "browser": true,
    "es6": true,
    "node": true,
    "commonjs": true
  },
  "extends": [ "eslint:recommended"],
  }
}

Dorothydorp

I just had to add "parser": "babel-eslint" to my .eslintrc.json file – Binaural

Answer 6

When working on the node js project. This might help you. It is working on my end.

module.exports = {
    "env": {
        "node": true,
        "browser": true,
        "commonjs": true,
        "es6": true
    },
    "extends": "eslint:recommended",
    "globals": {
        "Atomics": "readonly",
        "SharedArrayBuffer": "readonly"
    },
    "parserOptions": {
        "ecmaVersion": 2018
    },
    "rules": {
    }
};

Offal

Answer 7

If you are getting the error even after settng "node": true, remember to install @types/node with

npm i -D @types/node

yarn add -D @types/node

Yuriyuria

Answer 8

Add these env lines in your .eslintrc.js file.

module.exports = {
    "env": {
        "browser": true,
        "commonjs": true,
        "node": true,
        "es2021": true,
        "jest": true
    },
    "extends": "eslint:recommended",
    "parserOptions": {
        "ecmaVersion": "latest"
    },
    "rules": {
    }
}

Ruscher

Answer 9

In the new ESLint configuration file eslint.config.js, the env property has been removed so you should use the languageOptions.globals property:

import globals from 'globals';

export default [
  {
    languageOptions: {
      globals: {
        ...globals.node,
      }
    }
  }
];

Nedi

Answer 10

For a single file, when most other scripts are meant to run in a browser environment, you can add a special comment to the top of a file:

/* eslint-env node */

Note that it has to be a block comment style; an inline style comment (//) will not work.

Pejsach

Answer 11

Seems you need to enable Node Core library Within WebStorm:

1. Go to File -> Settings -> Languages & Frameworks -> Node.js and NPM
2. Make sure that 'Node.js Core library is enabled' by pressing Enable button.
3. Click OK for saving settings.

Intromit

Answer 12

Another remedy for this issue is to simply import process from "process".

Even though it's not strictly necessary, one could argue it's better practice anyway.

Libelous