Return to site

Add Bootstrap 4 to your Ruby on Rails 6 application

The right way

· Ruby on Rails,Bootstrap,Web App Development,Ruby on Rails 6

Use yarn to add Bootstrap and its dependencies - jquery and popper.js

Run the following command from your application directory (if you don't have yarn, install it):

yarn add bootstrap@4.3.1 jquery popper.js

You can check that the libraries have been installed properly by checking the package.json file (listed under the Gemfile.lock file in your file directory)

broken image

Now for JavaScript

Make the config/webpack/environment.js file look like below:

Make the config/webpack/environment.js file look like below (you are adding the lines which are highlighted in green below):

const { environment } = require('@rails/webpacker')

const webpack = require("webpack")

environment.plugins.append("Provide", new webpack.ProvidePlugin({

$: 'jquery',

jQuery: 'jquery',

Popper: ['popper.js', 'default']


module.exports = environment

This is so your application's javascript understands jquery and popper.js syntax.

Now you have to import bootstrap and it's goodies to your application.js, go to app/javascript/packs/application.js and add the following line to the bottom:

import "bootstrap"

That's it for javascript, now onto CSS

Now onto CSS

Go to app/assets/stylesheets/application.css and add the following line above the require_tree and require_self lines:

*= require bootstrap

So it looks like below:

*= require bootstrap

*= require_tree .

*= require_self

Now to add custom styles to the app styling, create a new file within this folder (app/assets/stylesheets folder) and call it custom.css.scss (app/assets/stylesheets/custom.css.scss).

Here import the bootstrap library first so you are able to modify styles for not just your new classes but existing bootstrap classes as well:

@import 'bootstrap/dist/css/bootstrap';

And that's it! you should be good to go with bootstrap 4 in your Rails 6 application. To test it out, you can add some bootstrap 4 classes (like navbar) to your application layout file and try changing it from this custom.css.scss file. Example test code below:


.navbar {

background-color: #FDF6EA !important;



.navbar-brand {

font-size: 3rem;



h1 {

color: red;


Good luck and enjoy!

- Mashrur