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webpack resolve error with packaged css file referencing an image

I'm working on a Vue component library built via VueCLI (and using Storybook Js, Bulma, and Buefy) and I am having issues consuming the CSS downstream. Specifically when I import the CSS file from my package, I am getting Webpack errors with referenced images.
For example, in my upstream src scss files I have a file called "notice-badge.scss" and am referencing background images like so:
.notice-badge img {
background-image: url('#/assets/img/warning-dark.svg');
}
and my src directory structure looks like:
my-app/
|--src/
|--assets/
|--scss/
|-- notice-badge.scss
|--img/
|--warning-dark.svg
|--fonts/
|--vue-components/
and I build the packages with this command which produces no errors.
vue-cli-service build --target lib --name my-ui-components ./src/index.ts
This outputs my JS, a CSS file, and 2 directories (img and fonts) into my "dist" directory. The images listed in my errors are infact inthere.
So over in another Vue cli app (and later Nuxt) I will be importing the CSS file and Vue components but I am getting a "can't resolve" error on that warning-dark.svg file:
Can't resolve /img/warning-dark.a45b259b.svg in /Users/myname/sites/my-app/ui-components/dist. My package also contains font awesome font files too (a business decision to include this all up stream)
So how can I get my downstream Vue CLI app to resolve the images and fonts referenced inside my node_modules dir?

You have (at least) 3 options:
Inline the images/fonts as data URLs.
Use a relative path in the output and require apps that install your package to move the image directory to the same path as the built CSS file.
Don't ship built CSS, but instead source SCSS files. That way file loading/moving can be handled with WebPack configuration in the app that uses it (using file_loader. You can include example configuration in your package to make this easier.
If you're writing a Vue component library, it probably makes most sense to use method 3. However from your description it seems like this may not be an option (the business decision you mention). Method 2 might be viable but I didn't try it nor seen someone else suggest it.
Inline
This method probably is easiest and has best performance. If your other SVGs are similar to the examples, it seems like they should all be relatively small files. There's few reasons for a component library to ship big images, so this might be sufficient for your use case.
If you're using WebPack 5, you can inline assets using "Asset Modules".
module: {
rules: [
{
test: /\.svg/,
type: 'asset/inline'
}
]
}
If you tried this, you may have run into the following problem.
Since Sass implementations don't provide url rewriting, all linked
assets must be relative to the output.
If you pass the generated CSS on to the css-loader, all urls must be
relative to the entry-file (e.g. main.scss).
If you're just generating CSS without passing it to the css-loader, it must be relative to your web root.
You can try replacing url('#/assets/img/warning-dark.svg') with url('../img/warning-dark.svg') (or whatever the path relative to the entrypoint is). Does it now properly inline them?

VueJS: Trying to compile two CSS files in /dist

I just began using Vue and I'm hitting a wall while trying to compile SCSS into separate files. I understand that any SCSS that I'm writing within components will be compiled into a single file (/dist/css/app[hash].css), but I would like separate files which aren't imported into any component for external use.
I have several SCSS files (frames.scss, lists.scss, and tables.scss ) that I would like to be compiled, minified, and prefixed into their own CSS files alongside the aforementioned CSS file.
I would like the build structure to look something like this (with the external CSS file existing alongside the app CSS file):
dist/
css/
app[hash].css
frames.css
lists.css
tables.css
I have very little experience with Webpack, so my vue.config.js file is currently empty and my postcss.config.js file is below:
module.exports = {
plugins: {
autoprefixer: {}
}
}
I've searched all over StackOverflow for a solution to no avail, so any help would be greatly appreciated!

For webpack 4, I think you want to look at mini-css-extract-plugin.
its a webpack plugin that, by, default, creates different files per input. You can use this with scss as you would expect. https://stackoverflow.com/a/53180597/6646536 might be a good example.
There is a similar tool i've used for webpack 3 here:
https://github.com/webpack-contrib/extract-text-webpack-plugin

CSS not added to /dist folder using Webpack 4 and MiniCssExtractPlugin

Issue
Would any Webpack config experts out there be able to tell me why I can't extract my css into the dist folder when running npm run build?
Repo is here: https://github.com/damodog/webpack4-boilerplate
Further info
To summarise, I've been working through the Webpack Guide docs and everything was going well. js and css was getting injected into my index.html file via <link> and <script> tags respectively. I've installed various loaders, plugins etc and split my configs out into common (shared), dev and prod files (as per the docs) and life was good.
I happened to make some tweaks which included looking at code splitting dynamic imports, adding aliases for paths, moving js into js folder etc and noticed when I ran a build npm run build all of a sudden my css wasn't getting added to the dist folder. I reverted my trial changes for the dynamic import stuff and tried reverting the other changes but am still getting the same issue. Annoyingly I hadn't added git at this point so didn't have a clear picture of the 'tweaks' I'd made to locate what I'd changed.
What happens
When I run my watch task npm start the styles.scss file (imported into the main index.js file) get's compiled into css and the resulting app.css file gets injected into the index.html page when viewed in my local host. All gravy.
<link href="css/app.css" rel="stylesheet">
When I run npm run build the css file should get copied over dist folder, a hash id should get added and the css should be minified. This was working (like I said above) and I could see the css file in the build steps (see first Asset below. Btw disregard the difference in js bundled files here compared to the next screenshot. This was when I was playing with code splitting).
Now when I run this the css isn't bundled up (see below).
I think it could be something to do with mini-css-extract-plugin but I've configured this as per the docs using the advanced configuration example (I've split their example out which is in one config file as I have separate config files for dev and prod).
I literally cannot see why this is happening.
Help me SO readers. You're my only help...

I cloned your repo and experimented with it. In your package.json, you've set: sideEffects: false. This causes the imported stylesheets to be lost in the process of tree shaking. This is described in the docs:
A "side effect" is defined as code that performs a special behavior
when imported, other than exposing one or more exports. An example of
this are polyfills, which affect the global scope and usually do not
provide an export.
and
Note that any imported file is subject to tree shaking. This means if
you use something like css-loader in your project and import a CSS
file, it needs to be added to the side effect list so it will not be
unintentionally dropped in production mode
So change your side effects in package.json to "sideEffects: ["./src/scss/styles.scss"] and it will be output to the destination folder when in production mode.

Webpack proper bootstrap loading with extract-text-webpack-plugin

I am trying to bundle css files with webpack extract-text-webpack-plugin it works great with local files that are int (projects)/src/assets/styles, but I also need bootstrap.css from node_modules and if I try adding it to import b from 'bootstrap/dist/css/bootstrap.css'; the plugin just throws an error that sounds something like this "bootstrap.css Unexpected token (7:5) You may need an appropriate loader to handle this file type." If I add '!style!css!' as described in this question
Webpack Error while including bootstrap 3 it does work, but now it is injected in index.html which may slowdown the overall app. So how do you correctly load the bootstrap style from node_modules? I tried copying it with copy-webpack-plugin, but the copying is performed after the loaders have done their job. so any suggestions?

With a bit more research and debuging the problem was in css loader path, which was pointed to the app source directory, that is why it could not access the node_modules.

how to use webpack to load CDN or external vendor javascript lib in js file, not in html file

I am using react starter kit for client side programming. It uses react and webpack. No index.html or any html to edit, all js files. My question is if I want to load a vendor js lib from cloud, how to do I do that?
It would be easy to do that in a html file. <script src="https://forio.com/tools/js-libs/1.5.0/epicenter.min.js"></script>
However, in js file, it only uses npm installed packages. How can I import the above lib with no html file? I tried import and require, they only work for local files.
update 10/21/15
So far I tried two directions, neither is ideal.
#minheq yes there is a html file sort of for react start kit. It is html.js under src/components/Html. I can put cloud lib and all its dependencies there like this:
<div id="app" dangerouslySetInnerHTML={{__html: this.props.body}} />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
<script src="https://forio.com/tools/js-libs/1.5.0/epicenter.min.js"></script>
<script src="/app.js"></script>
<script dangerouslySetInnerHTML={this.trackingCode()} />
</body>
Good news is it works, I don't need do anything else in js file, no import or require. However, now I have two jquery libs loaded in different ways. One in here, the other through npm and webpack. I wonder it will give me trouble later. The react-routing I use give me 'undefined variable' error if I type a none home path in browser window due to the server side loading I guess. So this solution is not very good.
Use webpack externals feature. This is documented as: link. "You can use the externals options for applications too, when you want to import an existing API into the bundle. I.e. you want to use jquery from CDN (separate tag) and still want to require("jquery") in your bundle. Just specify it as external: { externals: { jquery: "jQuery" } }."
However, the documentation I found a few places are all fussy about how to do this exactly. So far I have no idea how to use it to replace <script src="https://forio.com/tools/js-libs/1.5.0/epicenter.min.js"></script> in html.

externals is not intended to let you do this. It means "don't compile this resource into the final bundle because I will include it myself"
What you need is a script loader implementation such as script.js. I also wrote a simple app to compare different script loader implementations: link.

var $script = require("scriptjs");
$script("//ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js", function() {
$('body').html('It works!')
});

You can create a script tag in your JS as
$("body").append($("<script src="https://forio.com/tools/js-libs/1.5.0/epicenter.min.js"></script>"))

There is one html file that is definitely being used to serve to users with your js bundle attached. Probably you could attach the script tag into that html file

Use webpack's externals:
externals allows you to specify dependencies for your library that are
not resolved by webpack, but become dependencies of the output. This
means they are imported from the environment during runtime.

I have looked around for a solution and most of all proposals were based on externals, which is not valid in my case.
In this other post, I have posted my solution: https://stackoverflow.com/a/62603539/8650621
In other words, I finished using a separate JS file which is responsible for downloading the desired file into a local directory. Then WebPack scans this directory and bundles the downloaded files together with the application.