ESLint not working in VS Code?

Question

If ESLint is running in the terminal but not inside VSCode, it is probably because the extension is unable to detect both the local and the global node_modules folders.

To verify, press Ctrl+Shift+U in VSCode to open the Output panel after opening a JavaScript file with a known eslint issue. If it shows Failed to load the ESLint library for the document {documentName}.js -or- if the Problems tab shows an error or a warning that refers to eslint, then VSCode is having a problem trying to detect the path.

If yes, then set it manually by configuring the eslint.nodePath in the VSCode settings (settings.json). Give it the full path (for example, like "eslint.nodePath": "C:\\Program Files\\nodejs",) -- using environment variables is currently not supported.
This option has been documented at the ESLint extension page.

In my case, since I was using TypeScript with React, the fix was simply to tell ESLint to also validate these files. This needs to go in your user settings:

"eslint.validate": [ "javascript", "javascriptreact", "html", "typescriptreact" ],

configuring working directories solved it for me, since I had multiple projects with own .eslintrc files openend in the same window.

Put this in your .vscode/settings.json

"eslint.workingDirectories": [
    "./backend", 
    "./frontend"
],

thanks to this guy on github: https://github.com/microsoft/vscode-eslint/issues/696#issuecomment-542592372

PS: useful command to list all subdirectories containing an .eslintrc except /node_modules:

find . .eslintrc | grep .eslintrc | grep -v node_modules

There are a few reasons that ESLint may not be giving you feedback. ESLint is going to look for your configuration file first in your project and if it can't find a .eslintrc.json there it will look for a global configuration. Personally, I only install ESLint in each project and create a configuration based off of each project.

The second reason why you aren't getting feedback is that to get the feedback you have to define your linting rules in the .eslintrc.json. If there are no rules there, or you have no plugins installed then you have to define them.

Case 1/2: First-time plugin installation? approval is necessary

Little "weird" user experience (Hard to notice) - anyway - Since V 2.1.10 -
You must change the "currently block" status bar on New/First installation.

ESLint plugin Version 2.1.10 changelog (08/10/2020)

no modal dialog is shown when the ESLint extension tries to load an ESLint library for the first time and an approval is necessary. Instead the ESLint status bar item changes to ESLint status icon indicating that the execution is currently block.

Click on the status-bar (Right-Bottom corner):

Opens this popup:

Approve ==> Allows Everywhere

-or- by commands:

ctrl + Shift + p -- ESLint: Manage Library Execution

Read more here under "Release Notes":

https://marketplace.visualstudio.com/items?itemName=dbaeumer.vscode-eslint

---

Case 2/2: The plugin already installed/approve

Open the terminal Ctrl+`

Under output ESLint dropdown, you find useful debugging data (Errors, warnings, info).

For example, missing .eslintrc-.json throw this error:

Error: ENOENT: no such file or directory, realpath

Next, check if the plugin enabled:

By deafult there is no need to edit eslint.probe

Last, Since v 2.0.4 - eslint.validate in "normal cases" (react, vue, typescript, js, html, md) not necessary anymore (old legacy setting)**

**Many out-of-date stackoverflow answers (even her) indicate that eslint.probe file should be edited.

eslint.probe = an array for language identifiers for which the ESLint extension should be activated and should try to validate the file. If validation fails for probed languages the extension says silent. Defaults to [javascript, javascriptreact, typescript, typescriptreact, html, vue, markdown].

In my case, I had not installed he ESLint extension in VSCode, which was causing issue. Did it and it started working again.