Error importing local npm package

Question

We have several websites, each in its own project, and we are looking to migrate them all to using Vue.js. Each website has its own directory with .vue files that are then bundled using Webpack. We have a Webpack config in place that converts the .vue files, bundles, lints and pipes it all through babel and it works fine.

However, now that we have been moving things over for several weeks we have noticed that there are several components and core javascript files that are very similar and ideally we want to pull these out into a shared library of vue components and functions.

We have extracted several .vue into a folder alongside the websites, and put them together as a basic npm module with its own package.json, and include them using an npm file include, so in the package.json it just looks like: "vue-shared": "file:../CommonJavascript/Vue". Now when we try to use Webpack to build the bundle, we get the error:

ERROR in ../CommonJavascript/Vue/index.js Module build failed (from ./node_modules/eslint-loader/index.js): Error: Failed to load plugin react: Cannot find module 'eslint-plugin-react'

I'm not sure where this error is coming from, because we aren't using react anywhere, and it seemed happy enough to build fine before we moved the files out. At the moment the only dependency in the shared module is moment, and it only contains 4 .vue, and a basic wrapper to bundle them up:

import button from 'Button.vue'
import loading from 'Loading.vue'
import modal from 'Modal.vue'
import progressBar from 'ProgressBar.vue'

export default {
  button,
  loading,
  modal,
  progressBar,
}

But, I was curious so I decided to add the package (even though we don't need it) to see if it would fix the issue, but I then get a new error:

ERROR in ../CommonJavascript/Vue/index.js Module build failed (from ./node_modules/babel-loader/lib/index.js): ReferenceError: Unknown plugin "transform-runtime" specified in "base" at 0, attempted to resolve relative to "C:\Projects\Tmo\Code\CommonJavascript\Vue"

Now, that one makes a little more sense, we do use the babel runtime transform on the main project, but it isn't required by anything in the shared project and even if it was, surely the fact it is included in the main project means it should still build.

Partly, it seems perhaps I'm just not understanding the way npm resolves dependencies. It seems to be trying to now resolve some dependencies by looking in the shared files project and I dont know why. Also I have no idea where this strange dependency on eslint-plugin-react has come from.

So I guess this is a multi-part question. What is up with the way npm is trying to resolve the dependencies? Am I doing things right by moving the .vue files into a separate project, wrapping it up as a module and requiring it in the main project? and if not, what is the best way to have shared dependencies like this?

Answer 1

This was caused by a mixture of two separate issues:

• The import statements didn't reference the file properly, the correct syntax is: import button from './Button.vue' (note the change to file path)
• When you add a local package to npm via a path, it creates a symlink to the folder rather than copying the files over (this has been the behaviour since npm v5+). This then changes the way webpack tries to resolve dependencies since it then looks up from the location of the shared files to try and resolve dependencies including thing like eslint and babel.
• The eslint-plugin-react dependency was because in visual studio code I had installed the eslint plugin, which it seems had created a .eslintrc file which reference the react plugin in my user folder (c:\users\<username>). Eslint will then use this as the default if it can't find a config file (which it couldn't because it was looking above the shared files because of the pathing issues described above)

We have decided we will be using a git submodule for these files going forward