How to import CSS from node_modules in webpack angular2 app - css

Question

Let's say that we start with the following starter pack:
https://github.com/angularclass/angular2-webpack-starter
After npm install and npm run start everything works fine.
I want to add an external css module, for example bootstrap 4's css (and only the css). (I know that bootstrap has a bootstrap-loader, but now I'm asking for general solution, so please think about bootstrap 4 here as it could be any other css module that is available via npm).
I install bootstrap via npm: npm install bootstrap#4.0.0-alpha.4 --save
First I thought that it is enough to add import 'bootstrap/dist/css/bootstrap.css'; to the vendor.browser.ts file.
But it isn't.
What should I do to have a proper solution?
Solutions I'm NOT asking for:
"Copy the external css module to the assets folder, and use it from there"
I'm looking for a solution that works together with npm package.
"Use bootstrap-loader for webpack"
As I described above, I'm looking for a general solution, bootstrap is only an example here.
"Use another stack"
I'm looking for a solution in the exact starter pack that I've mentioned above.

Answer 1

It is possible by using #import '~bootstrap/dist/css/bootstrap.css'; on the styles.css file. (Note the ~)
Edit: How it works - The '~' is an alias set on the webpack config pointing to the assets folder... simple as that..
Edit 2: Example on how to configure webpack with the '~' alias...
this should go on the webpack config file (usually webpack.config.js)...
// look for the "resolve" property and add the following...
// you might need to require the asset like '~/bootsrap/...'
resolve: {
alias: {
'~': path.resolve('./node_modules')
}
}

Answer 2

You won't be able to import any css to your vendors file using that stack, without making some changes.
Why? Well because this line:
import 'bootstrap/dist/css/bootstrap.css';
It's only importing your css as string, when in reality what you want is your vendor css in a style tag. If you check config/webpack.commons.js you will find this rule:
{
test: /\.css$/,
loaders: ['to-string-loader', 'css-loader']
},
This rule allows your components to import the css files, basically this:
#Component({
selector: 'app',
encapsulation: ViewEncapsulation.None,
styleUrls: [
'./app.component.css' // this why you import css as string
],
In the AppComponent there's no encapsulation, because of this line encapsulation: ViewEncapsulation.None, which means any css rules will be applied globally to your app. So you can import the bootstrap styles in your app component:
#Component({
selector: 'app',
encapsulation: ViewEncapsulation.None,
styleUrls: [
'./app.component.css',
'../../node_modules/bootstrap/dist/css/bootstrap.css'
],
But if you insist in importing to your vendor.ts then you will need to install a new loader, npm i style-loader --save-dev this will allow webpack to inject css to your page. Then you need to create a specific rule, on your webpack.common.js and change the existing one:
{ //this rule will only be used for any vendors
test: /\.css$/,
loaders: ['style-loader', 'css-loader'],
include: [/node_modules/]
},
{
test: /\.css$/,
loaders: ['to-string-loader', 'css-loader'],
exclude: [/node_modules/] //add this line so we ignore css coming from node_modules
},
The firs rule will be only applied when you try to import css, from any package inside node_modules the second rule will be applied to any css that you import from outside the node_modules

Answer 3

So here is a way to import various CSS files using the angular-cli which I find the most convenient.
Basically, you can refer to the CSS files (order is important if you will be overriding them) in the config and angular-cli will take care of the rest. For instance, you might want to include a couple of styles from node-modules, which can be done as follows:
"styles": [
"../node_modules/font-awesome/css/font-awesome.min.css",
"../node_modules/primeng/resources/primeng.min.css",
"styles.css"
]
A sample full-config might look like this:
.angular-cli.json
{
"$schema": "./node_modules/#angular/cli/lib/config/schema.json",
"project": {
"name": "my-angular-app"
},
"apps": [
{
"root": "src",
"outDir": "dist",
"assets": [
"assets",
"favicon.ico"
],
"index": "index.html",
"main": "main.ts",
"polyfills": "polyfills.ts",
"test": "test.ts",
"tsconfig": "tsconfig.app.json",
"testTsconfig": "tsconfig.spec.json",
"prefix": "app",
"styles": [
"../node_modules/font-awesome/css/font-awesome.min.css",
"../node_modules/primeng/resources/primeng.min.css",
"styles.css"
],
"scripts": [],
"environmentSource": "environments/environment.ts",
"environments": {
"dev": "environments/environment.ts",
"prod": "environments/environment.prod.ts"
}
}
],
"e2e": {
"protractor": {
"config": "./protractor.conf.js"
}
},
"lint": [
{
"project": "src/tsconfig.app.json",
"exclude": "**/node_modules/**"
},
{
"project": "src/tsconfig.spec.json",
"exclude": "**/node_modules/**"
},
{
"project": "e2e/tsconfig.e2e.json",
"exclude": "**/node_modules/**"
}
],
"test": {
"karma": {
"config": "./karma.conf.js"
}
},
"defaults": {
"styleExt": "scss",
"component": {}
}
}