How to import CSS from node_modules in webpack angular2 app

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 [email protected] --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:

1. "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.

2. "Use bootstrap-loader for webpack"

• As I described above, I'm looking for a general solution, bootstrap is only an example here.

3. "Use another stack"

• I'm looking for a solution in the exact starter pack that I've mentioned above.

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')
  }
}

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

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": {}
  }
}