NPM 7/8 is not installing peer dependencies

Question

I'm trying to build a repository/package for my personal ESLint config files. I have all of my configuration files built the way I would like, and now I am trying to install this package to test it.

In this scenario, I have two packages:

• @me/eslint-config is the package containing my ESLint config files.
• test-package is the package on/in which I am trying to install @me/eslint-config.

When I try to install the @me/eslint-config package, peer dependencies are not installed, nor are they even mentioned during the installation.

Both packages currently only reside locally on my machine, side-by-side, in the same directory:

<parent_dir>:
  - eslint-config
    - package.json
    - ...
  - test-package
    - package.json
    - ...

The package.json file for @me/eslint-config looks as follows:

{
    ...
    "dependencies": {
        "@typescript-eslint/parser": "5.29.0"
    },
    "peerDependencies": {
        "eslint": "8.18.0",
        "eslint-plugin-import": "2.26.0",
        "eslint-plugin-jsdoc": "39.3.3",
        "eslint-plugin-prefer-arrow": "1.2.3",
        "@typescript-eslint/eslint-plugin": "5.29.0"
    }
    ...
}

I am installing this package in test-package as follows:

$> cd /path/to/test-package
$> npm i ../eslint-config --save-dev

NPM properly installs all other dependencies, including the @me/eslint-config package itself, but does not install the peerDependencies of @me/eslint-config.

This is using NPM v8.1.0.

This article seems to suggest that NPM >7 installs peer dependencies automatically. This is obviously not working for me.

Things I have already tried that have not fixed the problem:

• Deleting node_modules/ and package-lock.json from test-package and reinstalling everything.
• Pinning all peerDependencies versions in @me/eslint-config.
• Adding all peerDependencies in @me/eslint-config as both dependencies and peerDependencies in @me/eslint-config.

tl;dr NPM isn't installing peerDependencies

Nigrosine

Any luck of finding out why? I'm having the same issue right now. – Epimorphosis

Do you have a .npmrc file? Show the config. – Sherleysherline

Answer 1

I had the same error on former version of npm and as you mention, npm ^8 now install peer dependencies.

But here could be ways of fining your problem

1 : estlint is a devDependencies (A guess)

eslint should be devDependencies and not a peerDependencies.
Maybe npm doesn't accept you to install it then.

I search a bit but couldn't find any real thread discussing about this

That said, I wouldn't install it as dependencies since it will be pushed to your production build, what, I think, you do not want.

2 : Being up to date

Try it with the latest version of npm

1. download the latest version of npm : npm install -g npm@latest
2. Delet node_modules/ and package-lock.json from test-package and reinstall everything. as you did already

2 : allowJs

If eslint is an js package & you see it being installed in the node_modules folder.

1. Inside the tsconfig.json file, under the compilerOptions add allowJs: true and set strict: false

  "compilerOptions": {
    "allowJs": true,
    "strict": false,

2. Close all your instance of vs-code
3. Restart & retry (No need to remove the package-lock or so)

Scholasticism

Answer 2

What it worked for me is what is described in point 2. from Raphaël's answer:

$ npm cache clean --force
$ rm -rf node_modules package-lock.json
$ npm install

Unfortunately, I still don't understand why these steps solves the issue.

Athos