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Bootstrap & Webpack

关于如何使用 Webpack 在项目中包含和捆绑 Bootstrap 的 CSS 和 JavaScript 的官方指南。

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Want to skip to the end? Download the source code and working demo for this guide from the twbs/examples repository. You can also open the example in StackBlitz for live editing.

Setup

We’re building a Webpack project with Bootstrap from scratch, so there are some prerequisites and upfront steps before we can really get started. This guide requires you to have Node.js installed and some familiarity with the terminal.

  1. Create a project folder and set up npm. We’ll create the my-project folder and initialize npm with the -y argument to avoid it asking us all the interactive questions.

    mkdir my-project && cd my-project
npm init -y

  2. Install Webpack. Next we need to install our Webpack development dependencies: webpack for the core of Webpack, webpack-cli so we can run Webpack commands from the terminal, and webpack-dev-server so we can run a local development server. Additionally, we’ll install html-webpack-plugin to be able to store our index.html in src directory instead of the default dist one. We use --save-dev to signal that these dependencies are only for development use and not for production.

    npm i --save-dev webpack webpack-cli webpack-dev-server html-webpack-plugin

  3. Install Bootstrap. Now we can install Bootstrap. We’ll also install Popper since our dropdowns, popovers, and tooltips depend on it for their positioning. If you don’t plan on using those components, you can omit Popper here.

    npm i --save bootstrap @popperjs/core

  4. Install additional dependencies. In addition to Webpack and Bootstrap, we need a few more dependencies to properly import and bundle Bootstrap’s CSS and JS with Webpack. These include Sass, some loaders, and Autoprefixer.

    npm i --save-dev autoprefixer css-loader postcss-loader sass sass-loader style-loader

Now that we have all the necessary dependencies installed, we can get to work creating the project files and importing Bootstrap.

Project structure

We’ve already created the my-project folder and initialized npm. Now we’ll also create our src and dist folders to round out the project structure. Run the following from my-project, or manually create the folder and file structure shown below.

mkdir {src,src/js,src/scss}
touch src/index.html src/js/main.js src/scss/styles.scss webpack.config.js

When you’re done, your complete project should look like this:

my-project/
├── src/
│   ├── js/
│   │   └── main.js
│   ├── scss/
│   │   └── styles.scss
│   └── index.html
├── package-lock.json
├── package.json
└── webpack.config.js

At this point, everything is in the right place, but Webpack won’t work because we haven’t filled in our webpack.config.js yet.

Configure Webpack

With dependencies installed and our project folder ready for us to start coding, we can now configure Webpack and run our project locally.

  1. Open webpack.config.js in your editor. Since it’s blank, we’ll need to add some boilerplate config to it so we can start our server. This part of the config tells Webpack where to look for our project’s JavaScript, where to output the compiled code to (dist), and how the development server should behave (pulling from the dist folder with hot reload).

    'use strict'

const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')

module.exports = {
  mode: 'development',
  entry: './src/js/main.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist')
  },
  devServer: {
    static: path.resolve(__dirname, 'dist'),
    port: 8080,
    hot: true
  },
  plugins: [
    new HtmlWebpackPlugin({ template: './src/index.html' })
  ]
}

  2. Next we fill in our src/index.html. This is the HTML page Webpack will load in the browser to utilize the bundled CSS and JS we’ll add to it in later steps. Before we can do that, we have to give it something to render and include the output JS from the previous step.

    <!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Bootstrap w/ Webpack</title>
  </head>
  <body>
    <div class="container py-4 px-3 mx-auto">
      <h1>Hello, Bootstrap and Webpack!</h1>
      <button class="btn btn-primary">Primary button</button>
    </div>
  </body>
</html>

    We’re including a little bit of Bootstrap styling here with the div class="container" and <button> so that we see when Bootstrap’s CSS is loaded by Webpack.

  3. Now we need an npm script to run Webpack. Open package.json and add the start script shown below (you should already have the test script). We’ll use this script to start our local Webpack dev server. You can also add a build script shown below to build your project.

    {
  // ...
  "scripts": {
    "start": "webpack serve",
    "build": "webpack build --mode=production",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  // ...
}

  4. And finally, we can start Webpack. From the my-project folder in your terminal, run that newly added npm script:

    npm start

    Webpack dev server running

In the next and final section to this guide, we’ll set up the Webpack loaders and import all of Bootstrap’s CSS and JavaScript.

Import Bootstrap

Importing Bootstrap into Webpack requires the loaders we installed in the first section. We’ve installed them with npm, but now Webpack needs to be configured to use them.

  1. Set up the loaders in webpack.config.js. Your configuration file is now complete and should match the snippet below. The only new part here is the module section.

    'use strict'

const path = require('path')
const autoprefixer = require('autoprefixer')
const HtmlWebpackPlugin = require('html-webpack-plugin')

module.exports = {
  mode: 'development',
  entry: './src/js/main.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist')
  },
  devServer: {
    static: path.resolve(__dirname, 'dist'),
    port: 8080,
    hot: true
  },
  plugins: [
    new HtmlWebpackPlugin({ template: './src/index.html' })
  ],
  module: {
    rules: [
      {
        test: /\.(scss)$/,
        use: [
          {
            // Adds CSS to the DOM by injecting a `<style>` tag
            loader: 'style-loader'
          },
          {
            // Interprets `@import` and `url()` like `import/require()` and will resolve them
            loader: 'css-loader'
          },
          {
            // Loader for webpack to process CSS with PostCSS
            loader: 'postcss-loader',
            options: {
              postcssOptions: {
                plugins: [
                  autoprefixer
                ]
              }
            }
          },
          {
            // Loads a SASS/SCSS file and compiles it to CSS
            loader: 'sass-loader'
          }
        ]
      }
    ]
  }
}

    Here’s a recap of why we need all these loaders. style-loader injects the CSS into a <style> element in the <head> of the HTML page, css-loader helps with using @import and url(), postcss-loader is required for Autoprefixer, and sass-loader allows us to use Sass.

  2. Now, let’s import Bootstrap’s CSS. Add the following to src/scss/styles.scss to import all of Bootstrap’s source Sass.

    // Import all of Bootstrap's CSS
@import "bootstrap/scss/bootstrap";

    You can also import our stylesheets individually if you want. Read our Sass import docs for details.

  3. Next we load the CSS and import Bootstrap’s JavaScript. Add the following to src/js/main.js to load the CSS and import all of Bootstrap’s JS. Popper will be imported automatically through Bootstrap.

    // Import our custom CSS
import '../scss/styles.scss'

// Import all of Bootstrap's JS
import * as bootstrap from 'bootstrap'

    You can also import JavaScript plugins individually as needed to keep bundle sizes down:

    import Alert from 'bootstrap/js/dist/alert'

// or, specify which plugins you need:
import { Tooltip, Toast, Popover } from 'bootstrap'

    Read our JavaScript docs for more information on how to use Bootstrap’s plugins.

  4. And you’re done! 🎉 With Bootstrap’s source Sass and JS fully loaded, your local development server should now look like this:

    Webpack dev server running with Bootstrap

    Now you can start adding any Bootstrap components you want to use. Be sure to check out the complete Webpack example project for how to include additional custom Sass and optimize your build by importing only the parts of Bootstrap’s CSS and JS that you need.

Production optimizations

Depending on your setup, you may want to implement some additional security and speed optimizations useful for running the project in production. Note that these optimizations are not applied on the Webpack example project and are up to you to implement.

Extracting CSS

The style-loader we configured above conveniently emits CSS into the bundle so that manually loading a CSS file in dist/index.html isn’t necessary. This approach may not work with a strict Content Security Policy, however, and it may become a bottleneck in your application due to the large bundle size.

To separate the CSS so that we can load it directly from dist/index.html, use the mini-css-extract-loader Webpack plugin.

First, install the plugin:

npm install --save-dev mini-css-extract-plugin

Then instantiate and use the plugin in the Webpack configuration:

--- a/webpack.config.js
+++ b/webpack.config.js
@@ -3,6 +3,7 @@
 const path = require('path')
 const autoprefixer = require('autoprefixer')
 const HtmlWebpackPlugin = require('html-webpack-plugin')
+const miniCssExtractPlugin = require('mini-css-extract-plugin')

 module.exports = {
   mode: 'development',
@@ -17,7 +18,8 @@ module.exports = {
     hot: true
   },
   plugins: [
-    new HtmlWebpackPlugin({ template: './src/index.html' })
+    new HtmlWebpackPlugin({ template: './src/index.html' }),
+    new miniCssExtractPlugin()
   ],
   module: {
     rules: [
@@ -25,8 +27,8 @@ module.exports = {
         test: /\.(scss)$/,
         use: [
           {
-            // Adds CSS to the DOM by injecting a `<style>` tag
-            loader: 'style-loader'
+            // Extracts CSS for each JS file that includes CSS
+            loader: miniCssExtractPlugin.loader
           },
           {

After running npm run build again, there will be a new file dist/main.css, which will contain all of the CSS imported by src/js/main.js. If you view dist/index.html in your browser now, the style will be missing, as it is now in dist/main.css. You can include the generated CSS in dist/index.html like this:

--- a/dist/index.html
+++ b/dist/index.html
@@ -3,6 +3,7 @@
   <head>
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
+    <link rel="stylesheet" href="./main.css">
     <title>Bootstrap w/ Webpack</title>
   </head>
   <body>

Extracting SVG files

Bootstrap’s CSS includes multiple references to SVG files via inline data: URIs. If you define a Content Security Policy for your project that blocks data: URIs for images, then these SVG files will not load. You can get around this problem by extracting the inline SVG files using Webpack’s asset modules feature.

Configure Webpack to extract inline SVG files like this:

--- a/webpack.config.js
+++ b/webpack.config.js
@@ -23,6 +23,14 @@ module.exports = {
   },
   module: {
     rules: [
+      {
+        mimetype: 'image/svg+xml',
+        scheme: 'data',
+        type: 'asset/resource',
+        generator: {
+          filename: 'icons/[hash].svg'
+        }
+      },
       {
         test: /\.(scss)$/,
         use: [

After running npm run build again, you’ll find the SVG files extracted into dist/icons and properly referenced from CSS.

See something wrong or out of date here? Please open an issue on GitHub. Need help troubleshooting? Search or start a discussion on GitHub.