New to the web platform in February

Discover some of the interesting features that have landed in stable and beta web browsers during February 2024.

Rachel Andrew

Stable browser releases

In February 2024 Firefox 123 and Chrome 122 became stable. This post looks at the new features added to the web platform.

Declarative Shadow DOM

Firefox 123 supports the shadowrootmode attribute of the <template> element, thus supporting the Declarative Shadow DOM. This feature now joins Baseline newly available, as it is interoperable across all key browsers.

103 Early Hints: preload

Firefox 123 includes the 103 Early Hints status code for preloading resources.

Changes to CSS ::backdrop inheritance

The ::backdrop CSS pseudo-element is a box the size of the viewport, rendered immediately beneath any element that is presented in the top layer. The original specification for ::backdrop specified that it did not inherit from any element, and is not inherited from. This meant that ::backdrop did not have access to custom properties declared on :root.

The specification has been changed to allow ::backdrop to inherit properties from its originating element. This change is implemented in Chrome 122.

Read more about the changes to ::backdrop.

Storage Buckets API

Chrome 122 includes the Storage Buckets API. This API gives sites the ability to organize on-device data into buckets, the group data can then be evicted independently of data held in other buckets.

Learn more in the Storage Buckets API documentation.

Async Clipboard API: Read unsanitized HTML

Chrome 122 beta includes an unsanitized option in the read() method of the Async Clipboard API to retrieve unsanitized HTML format.

JavaScript Set methods

Chrome 122 implements the following methods of Set:

• difference
• intersection
• isDisjointFrom
• isSubsetOf
• isSuperSetOf
• symetricDifference
• union

These methods are already implemented in Safari, from version 17, and are in Firefox Nightly.

Beta browser releases

Beta browser versions give you a preview of things that will be in the next stable version of the browser. It's a great time to test new features, or removals, that could impact your site before the world gets that release. New betas are Firefox 124, Chrome 123 released this month, and Safari 17.4 is ongoing. These releases bring many great features to the platform. Check out the release notes for all of the details. Here are just a few highlights.

Chrome 123 includes several new CSS features. The light-dark() color function makes it easier to adapt color schemes to user preference. The field-sizing property enables automatically-growing text input fields. There is a new media feature to test for apps that are being shown in picture-in-picture mode.

The text-spacing-trim property applies kerning to Chinese, Japanese, and Korean (CJK) punctuation characters to adjust excessive spacing. Read more in Introducing four new international features for CSS.

In the Chrome 123 and Safari 17.4 betas is support for align-content in block and table layout. Read about the change to align-content support. Test your sites if you may be using the property outside of grid or flex layouts, as it will begin to cause alignment where previously it was not functional in block layout.

Firefox 124 includes support for the CSS content-visibility property. This property controls whether an element renders its content at all, allowing browsers to omit rendering the content until it is needed.