How can I use Bootstrap 5 with Next.js?

After installing bootstrap with npm install bootstrap I added the style to /pages/_app.js like so:

import 'bootstrap/dist/css/bootstrap.css';
export default function App({ Component, pageProps }) {
    return <Component {...pageProps} />
}

However anything from it that uses javascript does not work at all, e.g. the Collapse example from their docs.

function App() {
    return (
      <div>
        <p>
          <a class="btn btn-primary" data-bs-toggle="collapse" href="#collapseExample" role="button" aria-expanded="false" aria-controls="collapseExample">
            Link with href
          </a>
          <button class="btn btn-primary" type="button" data-bs-toggle="collapse" data-bs-target="#collapseExample" aria-expanded="false" aria-controls="collapseExample">
            Button with data-bs-target
          </button>
        </p>
        <div class="collapse" id="collapseExample">
          <div class="card card-body">
            Some placeholder content for the collapse component. This panel is hidden by default but revealed when the user activates the relevant trigger.
          </div>
        </div>
      </div>
    );
}
export default App

If I add import 'bootstrap/dist/js/bootstrap.js' to /pages/_app.js then it starts “working” as expected, until a page reload in which it says ReferenceError: document is not defined (screenshot), which leads me to believe it’s not possible or that I shouldn’t try to use boostrap + react or next.js.
I had thought them dropping jquery meant that it should work just “out of the box” with frameworks like react (as in not needing react-boostrap or reactstrap anymore)

Is there a way to properly use boostrap 5 and nextjs? Or should I just try something else entirely or go back to using reactstrap (which currently seems to only support boostrap 4)?

Answer

This is a common thing that most of us miss while switching to NextJS.

Problem: Document is not defined.

Reason: NextJS renders your app at server, and there is no window, document etc. on server, hence document is not defined. you can even console.log(typeof window, typeof document) to verify this.

NOW, what is the solution?

I used this code in my function component:

    useEffect(() => {
        typeof document !== undefined ? require('bootstrap/dist/js/bootstrap') : null
    }, [])

useEffect with empty dependencies works like componentDidMount() which runs after the code is run second time. Since code runs first at server and then at client, it will not produce errors, as client has document.

I’ve never used `componentDidMount(), ever.

Did that worked for me?

I just copied your Collapse example in my other app to verify this.