Using Bootstrap 5 with Vue 3

Yes, you can use Bootstrap without Bootstrap-Vue. Install these two packages with npm:

npm install --save @popperjs/core bootstrap@next

Import Bootstrap to src/main.js:

import "bootstrap/dist/css/bootstrap.min.css";
import "bootstrap";

Example usage for Vue Template:

<div class="dropdown">
    <button
      class="btn btn-secondary dropdown-toggle"
      type="button"
      id="dropdownMenuButton1"
      data-bs-toggle="dropdown"
      aria-expanded="false"
    >
      Check Bootstrap
    </button>
    <ul class="dropdown-menu" aria-labelledby="dropdownMenuButton1">
      <li><a class="dropdown-item" href="#">Action</a></li>
      <li><a class="dropdown-item" href="#">Another action</a></li>
      <li><a class="dropdown-item" href="#">Something else here</a></li>
    </ul>
  </div>

Result:

While the Bootstrap CSS can be used with any framework (React, Vue, Angular, etc), the Bootstrap JavaScript is not fully compatible with them.

Here's the official reasoning from the Bootstrap 5 docs:

While the Bootstrap CSS can be used with any framework, the Bootstrap JavaScript is not fully compatible with JavaScript frameworks like React, Vue, and Angular which assume full knowledge of the DOM. Both Bootstrap and the framework may attempt to mutate the same DOM element, resulting in bugs like dropdowns that are stuck in the “open” position.

The docs state to use an alternative framework-specific package instead of the Bootstrap JavaScript such as React Bootstrap, BootstrapVue, and ng-bootstrap.

Unfortunately, BootstrapVue is only compatible with Vue2/Nuxt2 and there is no version available for Vue3/Nuxt3 yet.

It's easy to implement this once you understand how Bootstrap modals work. Bootstrap modals have a div element with a class of modal fade. When it is triggered, this element gets the show and d-block class as well. In addition, the body tag gets an additional class of modal-open. When the modal is closed, this process is reversed. Understanding this, we can easily implement Bootstrap 5 modals in one's code:

Import Bootstrap 5's CDN in your code. Add both the CSS and JS to your code.

Our sample Single Page Component will look like this:

<template>
<div>  
    <p>Test modal<a href="#" @click="modalToggle">now</a></p>
    <div>
        <button type="button" class="btn btn-primary" @click="modalToggle">My Modal</button>
            <div
            ref="modal"
            class="modal fade"
            :class="{ show: active, 'd-block': active }"
            tabindex="-1"
            role="dialog">
            <div class="modal-dialog" role="document">
            <div class="modal-content">
                <div class="modal-header">
                <h5 class="modal-title">Modal title</h5>
                <button
                    type="button"
                    class="close"
                    data-dismiss="modal"
                    aria-label="Close"
                    @click="modalToggle">
                    <span aria-hidden="true">&times;</span>
                </button>
                </div>
                <div class="modal-body">
                <p>Modal body text goes here.</p>
                </div>
            </div>
            </div>
        </div>
        <div v-if="active" class="modal-backdrop fade show"></div>
        </div>
</div>
</template>

Here we are using the basic Bootstrap 5 modal.

<script>
export default {
data() {
    return {
    active: false,
    }
},
methods: {
    modalToggle() {
    const body = document.querySelector("body")
    this.active = !this.active
    this.active ? body.classList.add("modal-open") : body.classList.remove("modal-open")
    },
},
}
</script>

Here, we have a variable active which is initially set false. So modal will not show up on page load. On clicking a link, we use a method to toggle this variable. This will remove the show attribute and the d-block class from our modalm and remove the modal-open property from the body tag.

bootstrap 5 must have popper for run, try with this npm:

npm install --save bootstrap 
npm i @popperjs/core

npm install --save bootstrap @popperjs/core

main.js or main.ts

import "bootstrap/dist/css/bootstrap.min.css"
import "bootstrap"

then use in code like this

<template>
  <div class="container">
    <h1 class="text-center my-5">Hello, Bootstrap with Vue 3!</h1>
    <button type="button" class="btn btn-primary">Primary Button</button>
  </div>
</template>

Going tag on to this answer however late it is, probably because I'll end up doing this again in a few months for another client.

I'm porting over a template from StartBootstrap into Vue, specifically the SB Admin 2 template and initially I couldn't get the navbar dropdown menu's to work. Turns out, the data attributes changed I guess between BS 4 and BS 5

Previous

<a
            class="nav-link collapsed"
            href="#"
            data-toggle="collapse"
            data-target="#collapseTwo"
            aria-expanded="true"
            aria-controls="collapseTwo"
          >
            <i class="fas fa-fw fa-cog"></i>
            <span>Components</span>
          </a>
          <div
            id="collapseTwo"
            class="collapse"
            aria-labelledby="headingTwo"
            data-parent="#accordionSidebar"
          >
            <div class="bg-white py-2 collapse-inner rounded">
              <h6 class="collapse-header">Custom Components:</h6>
              <a class="collapse-item" href="buttons.html">Buttons</a>
              <a class="collapse-item" href="cards.html">Cards</a>
            </div>
          </div>

You need to add -bs to the existing data- attributes as long as those attributes previously reference bootstrap functionality. Don't just go and do a Cntrl-F and Replace please.

Here is the after of the above example .

<a
            class="nav-link collapsed"
            href="#"
            data-bs-toggle="collapse"
            data-bs-target="#collapseTwo"
            aria-expanded="true"
            aria-controls="collapseTwo"
          >
            <i class="fas fa-fw fa-cog"></i>
            <span>Components</span>
          </a>
          <div
            id="collapseTwo"
            class="collapse"
            aria-labelledby="headingTwo"
            data-parent="#accordionSidebar"
          >
            <div class="bg-white py-2 collapse-inner rounded">
              <h6 class="collapse-header">Custom Components:</h6>
              <a class="collapse-item" href="buttons.html">Buttons</a>
              <a class="collapse-item" href="cards.html">Cards</a>
            </div>
          </div>

EDIT: The above assumes you've followed this answer already

https://stackoverflow.com/a/65555991/3689435

please add this package : npm install --save @popperjs/core