Hey there! Let me clear up the confusion between these two files for you—this is a super common question when getting started with Bootstrap 4:

Core Differences #

• bootstrap.min.js: This is the stripped-down, core JavaScript file for Bootstrap. It only contains Bootstrap's own component logic (like the code behind modals, tabs, carousels, etc.), and does NOT include any external dependencies. If you use this file, you'll need to separately include two key libraries for certain components to work:

  • jQuery (required for most interactive Bootstrap components like modals and tab switches)
  • Popper.js (required for dropdowns, tooltips, and popovers to position correctly relative to their trigger elements)

• bootstrap.bundle.min.js: This is the "all-in-one" bundled version. It includes everything in bootstrap.min.js, plus a compressed copy of Popper.js right inside the file. This means you don't need to add a separate <script> tag for Popper.js—saving you an extra HTTP request and simplifying your setup. Important note: It still does NOT include jQuery, so you'll still need to add jQuery separately if your project uses components that rely on it.

What's the "Extra Code" in the Bundle? #

The additional code in bootstrap.bundle.min.js is exactly the minified version of Popper.js. Popper.js is a lightweight library that handles dynamic element positioning—Bootstrap uses it to make sure dropdowns, tooltips, and popovers appear in the right spot (e.g., below a button, to the side of an input) without overlapping outside the viewport or breaking layout.

Which Should You Use? #

• Go with bootstrap.min.js if you already have Popper.js included in your project (maybe for another library that uses it) to avoid duplicate code.
• Choose bootstrap.bundle.min.js for quicker setup, especially if you're building a simple project and want to minimize the number of external script files you need to manage.

内容的提问来源于stack exchange，提问作者Michael Cole