IE Conditional Comment support is deprecated

By gapple on 26 October 2020

Change record status:

Published (View all published change records)

Project:

Drupal core

Introduced in branch:

9.1.x

Introduced in version:

9.1.0

Issue links:

https://www.drupal.org/node/3095113

Description:

The 'browsers' property of library assets is deprecated in Drupal 9.1 and is removed from Drupal 10.

Internet Explorer up to version 9 supported Conditional Comments to control a document's markup according to browser version.
Internet Explorer 9 and 10 support was dropped from Drupal 8.4.x, and no other supported browsers support Conditional Comments.

Themes can still conditionally include assets for IE <= 9 by adding markup in the html.html.twig template:

    <css-placeholder token="{{ placeholder_token }}">
    <!--[if lte IE 9]>
      <link rel="stylesheet" type="text/css" href="/themes/custom/THEME_NAME/assets/css/ie9.css" media="screen" />
      <script src="/themes/custom/THEME_NAME/assets/vendor/classList/classList.min.js"></script>
    <![endif]-->
    <js-placeholder token="{{ placeholder_token }}">

Impacts:

Module developers

Themers

Updates Done (doc team, etc.)

Online documentation:

Not done

Theming guide:

Not done

Module developer documentation:

Not done

Examples project:

Not done