Bootstrap 4 for IE8 and IE9

Bootstrap 4 drops support for Internet Explorer 8 and 9, but you can add it back by simply adding a conditional statement targeting IE 8 and 9 with a CSS file and a CDN-hosted JavaScript file to polyfill HTML5 element support.

Quick start

Several quick start options are available:

Download the latest release
Clone the repo git clone https://github.com/coliff/bootstrap-ie8.git
Install with npm npm install bootstrap-ie8
Install with yarn yarn add bootstrap-ie8
Install with Composer composer require coliff/bootstrap-ie8:4.3.1

Usage

Add <meta http-equiv="x-ua-compatible" content="ie=edge"> to the top of the of your page
Add the following conditional statements to the <head> of your page but after the Bootstrap 4 CSS:

<!--[if IE 9]>
  <link href="https://cdn.jsdelivr.net/gh/coliff/bootstrap-ie8/css/bootstrap-ie9.min.css" rel="stylesheet">
<![endif]-->
<!--[if lte IE 8]>
  <link href="https://cdn.jsdelivr.net/gh/coliff/bootstrap-ie8/css/bootstrap-ie8.min.css" rel="stylesheet">
  <script src="https://cdn.jsdelivr.net/g/html5shiv@3.7.3"></script>
<![endif]-->

Optional JavaScript Fix

To fix the dropdown menus and modals you can add the following to the footer:

<!--[if gte IE 9]><!-->
  <script src="https://code.jquery.com/jquery-3.4.1.slim.min.js"></script>
  <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.0/js/bootstrap.bundle.min.js"></script>
<!--<![endif]-->
<!--[if IE 9]>
  <script src="https://cdn.jsdelivr.net/gh/coliff/bootstrap-ie8/js/bootstrap-ie9.min.js"></script>
<![endif]-->
<!--[if lte IE 8]>
  <script src="https://code.jquery.com/jquery-1.12.4.min.js"></script>
  <script src="https://cdn.jsdelivr.net/gh/coliff/bootstrap-ie8/js/bootstrap-ie8.min.js"></script>
  <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.0/js/bootstrap.js"></script>
<![endif]-->

This will load jQuery, PopperJS and Bootstrap as normal on all browsers other than IE8. IE9 will load the bootstrap-ie9.js script. IE8 will load the latest compatible version of jQuery, the unminified Bootstrap JS (the minified version causes an error) and the bootstrap-ie8.js fix.

FAQS

Q. What does this fix/polyfill?

A. Internet Explorer 9 doesn't support flexbox so there is a float-based layout fallback and a couple of other minor fixes. Internet Explorer 8 doesn't support rem units so all units are specified in pixels. Media Queries are also not supported so IE8 has a fixed-width layout (min-width 998px).

Q. Is the CSS hosted on a CDN?

A. Yes, thanks to JSDelivr minified versions are available with the direct links:

Q. Will you provide LESS/SASS files?

A. Maybe in a future release I'll provide SASS file (with comments).

Q. Do I need the RespondJS polyfill for IE8 like Bootstrap 3 uses?

A. No. Instead the CSS is set to be fixed-width which makes things a lot easier. You don't need to change your HTML markup, the CSS will take care of it as the (min-width:992px) media queries are all set.

Q. Where can I see a demo?

A. Right here: http://coliff.github.io/bootstrap-ie8/test.htm

Q. I don't have access to IE8/IE9 browser to test- how can I see how my site appears?

A. You can use free virtual machines from Microsoft or use Browserstack.