Loading multiple stylesheet for a component in Angular2

问题

I am building an angular2 application. I am facing multiple problems when i try to load multiple stylesheet for the same component. Here is a the code of what i am doing:

import { Component } from '@angular/core';

@Component({
selector: 'my-tag',
templateUrl: 'my-tag.component.html',
styleUrls: [
    './style1.css',
    './style2.css'
    ]
})
export class MyTagComponent{}

Now here are my problems:

When i try to include the the css file from other directory like this:

styleUrls: [
    './style1.css',
    '../public/style2.css'
]

I get the error

Uncaught Error: Expected 'styles' to be an array of strings.

in browser console.

I then included the second stylesheet style2.css in the directory of the component and wrote the first snippet. Now the style is being loaded but it is being loaded globally. The second stylesheet has class names that clash with the bootstrap and instead of bootstrap's style the second stylesheet's style is being applied globally, i.e. other components' templates are being styled from second stylesheet.

Shouldn't the urls listed in styleUrls be applied only on the component and not do harm to other components?

Can anyone tell me how to load multiple css files for the a specific component without being applied globally.

I have also tried the following workarounds but the style is being applied on all the components that i made.

styles: [
      require('./style1.css').toString(),
      require('../public/style2.css').toString()
 ]

P.S. I am using webpack as the module bundler for my project.

webpack.config(excerpt)

 {
    test: /\.css$/,
    exclude: helpers.root('src', 'app'),
    loader: ExtractTextPlugin.extract('style', 'css?sourceMap')
  },
  {
    test: /\.css$/,
    include: helpers.root('src', 'app'),
    loader: 'raw'
  }

回答1:

I have seen this approach used:

@Component({
    selector: 'app',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent {
}

Where app.component.css has multiple imports in it, thus:

@import url('/assets/plugins/bootstrap-datepicker/css/bootstrap-datepicker.css');
@import url('/assets/plugins/bootstrap-datepicker/css/bootstrap-datepicker3.css');
@import url('/assets/plugins/ionRangeSlider/css/ion.rangeSlider.css');
@import url('/assets/plugins/ionRangeSlider/css/ion.rangeSlider.skinNice.css');

I hope this helps.

回答2:

We include the template and CSS files by setting the templateUrl and styleUrls metadata properties respectively. Because these files are co-located with the component, it would be nice to refer to them by name without also having to specify a path back to the root of the application.

We can change the way Angular calculates the full URL be setting the component metadata's moduleId property to module.id.

@Component({
  selector: 'my-tag',
  moduleId: module.id,
  templateUrl: 'my-tag.component.html',
  styleUrls:  ['style1.css', 'style2.css']
})
export class MyTagComponent { }

Update#1

for webpack:

Try to use the 'to-string-loader' for css in webpack config.

{ test: /\.css$/, loaders: ['to-string-loader', 'css-loader'] }

Hope will work for you.

回答3:

I believe the problem is with the 'style' argument you pass to ExtractPlugin.extract(loader: options|object). I think it refers to this loader: https://github.com/webpack/style-loader which adds a style tag to the DOM and so will apply your styles globally.

I ran into this problem the other day and only looked up the above justification for the sake of this post and should go back and fix it properly with that in mind, but I got around it by simply using the css-loader like this:

  {
    test: /\.css$/,
    loader: "css-loader"
  }

as well as setting the encapsulation to ViewEncapsulation.Native and, as you noted earlier, calling .toString() on the loaded CSS. I imagine that the ExtractTextPlugin could still be used instead with the 'style' loader removed, though.

来源：https://stackoverflow.com/questions/40763056/loading-multiple-stylesheet-for-a-component-in-angular2

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