[developer-signals] weekly digest

WebDX CG developer-signals weekly digest

web-platform-dx/developer-signals

This is an automated email summarizing recent activity on the  
developer-signals repo, which is where web developers add their support for  
web features that are not yet implemented in all major browsers.


A significant discussion emerged around the Custom Highlights API, which  
received 14 new upvotes and 23 new comments from developers at Google,  
Microsoft, Mozilla, and the Financial Times. The thread explores diverse  
use cases like syntax highlighting, text annotation, and custom  
find-in-page functionality, alongside a debate on performance versus  
traditional DOM manipulation. The strong momentum from the previous period  
continued for JPEG XL and Anchor positioning, with the former receiving a  
new use case for optimizing assets in web-based document editors. Several  
other CSS features also saw increased support, particularly Custom media  
queries and `attr()`, each gaining 8 new upvotes.


64 active features


Custom highlights (#179)

👍 +14
💬 +23
"The main use for this feature that I've personally encountered is for  
custom "find" functionality in dynamic applications. Think of a file e..."  
(@mayank99)
"I am currently working with text annotations. One project that I really  
like is recogito-js. Their renderers currently include the CSS highl..."  
(@Aierie)
"CSS Custom Highlights are essential for things like Syntax Highlighting  
code snippets without the div soup: https://www.bram.us/2024/02/18/c..."  
(@bramus)
"@bramus I love that demo, but how is div soup worse than range soup? I get  
that ranges are currently out of sight in eg the elements panel, ..."  
(@jakearchibald)
"@Aierie given that you're creating interactive areas, isn't doing this  
with the highlighting API an a11y issue?..." (@jakearchibald)
"This might be a specific niche but I'm using this API for a faux-textarea  
where a user can highlight a subset of the contained text which wi..."  
(@ryantownsend)
"Happy user of Highlight API. I use it a ton on projectwallace.com for  
several reasons: - No `<span>` soup means I can keep my DOM size smal..."  
(@bartveneman)
"@bartveneman I'm interested to hear more about the performance issues.  
 From my (potentially incorrect) understanding, creating and maintaini..."  
(@jakearchibald)
"## What I want to do with this feature Backend side, we analyze some raw  
texts and produce semantic text tags in the form of a specific sem..."  
(@sroucheray)
"## What I want to do with this feature We use it to render underlines  
under grammar/spelling errors in text written by users across the web..."  
(@qbsaumitra)
"I've been using it for syntax highlighting, and for bookmarklets that  
highlights typographical errors on a page...." (@johannesodland)
"@emilio mentioned this use-case: ## What I want to do with this feature  
Dynamically syntax highlight parts of the large code sample as it'..."  
(@jakearchibald)
"[Via](https://via.hypothes.is/https://www.youtube.com/watch?v=u9YiM7LZ6b0)  
is a YouTube video transcript annotation tool. It has a search fe..."  
(@robertknight)
"Related to the above, the associated [Hypothesis web annotation  
tool](https://github.com/hypothesis/client) would benefit from having a  
way ..." (@robertknight)
"For me, CSS Highlight is a completely unique low-level feature that allows  
styling of _partial_ text nodes without the addition of extra DOM..."  
(@zachleat)
"We've [tried to use it at  
GitLab](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/215286/diffs)  
for syntax highlighting in diffs but u..." (@CyberAP)
"@CyberAP curious, do you have profiles / did you file performance bugs on  
browsers? I was considering doing the same for Firefox's "view sou..."  
(@emilio)
"@emilio The steps listed in https://issues.chromium.org/issues/325589486  
get you there. When then scrolling quickly through the page, you'll..."  
(@bramus)
"I found it very useful for highlighting errors in text without touching  
the DOM: https://chrome.dev/web-ai-demos/proofreader-api-playground/..."  
(@tomayac)
"@bramus Have you tried scoping the highlight pseudo selectors? We found  
that scoping correctly brings a dramatic improvement to the scroll p..."  
(@qbsaumitra)
"> [@bramus](https://github.com/bramus) Have you tried scoping the  
highlight pseudo selectors? We found that scoping correctly brings a  
drama..." (@emilio)
"> [@emilio](https://github.com/emilio) The steps listed in  
https://issues.chromium.org/issues/325589486 get you there. When then  
scrolling q..." (@emilio)
"Ah, the explanation is that we had landed improvements for this like, just  
yesterday, in [bug 2011011](https://bugzilla.mozilla.org/show_bug..."  
(@emilio)

JPEG XL (#215)

👍 +8
💬 +1
"## What I want to do with this feature I work developing a web-based  
markdown editor to make TTRPG books(https://homebrewery.naturalcrit.co..."  
(@5e-Cleric)

Custom media queries (#445)

👍 +8

attr() (#293)

👍 +8

sibling-count() and sibling-index() (#361)

👍 +7

Customizable <select> (#278)

👍 +7

Anchor positioning (#245)

👍 +7

text-box (#265)

👍 +6

shape() (#443)

👍 +5

corner-shape (#398)

👍 +5

if() (#303)

👍 +4

Temporal (#291)

👍 +4

contrast-color() (#295)

👍 +3
💬 +1
"Can't wait for this feature. With the combination of relative colors I  
would be able to find any text color contrast with any hue! This woul..."  
(@AceCodePt)

<dialog closedby> (#279)

👍 +3

Container scroll-state queries (#272)

👍 +3

line-clamp (#267)

👍 +3

WebGPU (#202)

👍 +3

progress() (#444)

👍 +2

::scroll-button (#316)

👍 +2

Masonry (#308)

👍 +2

@function (#300)

👍 +2

:has-slotted (#276)

👍 +2

popover="hint" (#274)

👍 +2

initial-letter (#189)

👍 +2

Explicit resource management (#366)

👍 +1
💬 +1
"## What I want to do with this feature As part of development for the  
Satellite.js library, I'm creating a WebAssembly option to propagate ..."  
(@1valdis)

Scroll marker target pseudo-classes (#476)

👍 +1

Anchor position container queries (#466)

👍 +1

Range syntax for style queries (#465)

👍 +1

at-rule() (#447)

👍 +1

justify-self in block layouts (#442)

👍 +1

Top-level await (#441)

👍 +1

caret-shape (#424)

👍 +1

IndexedDB getAllRecords() (#422)

👍 +1

Map getOrInsert() (#399)

👍 +1

Sanitizer API (#363)

👍 +1

Gap decorations (#362)

👍 +1

:target-within (#320)

👍 +1

Speech recognition (#318)

👍 +1

Rhythmic sizing (#315)

👍 +1

path() (#313)

👍 +1

overflow-clip-margin (#311)

👍 +1

<link rel="prefetch"> (#306)

👍 +1

image() (#304)

👍 +1

fit-content() (#299)

👍 +1

display: contents (#296)

👍 +1

::column (#294)

👍 +1

Scroll markers (#289)

👍 +1

font-variant-emoji (#262)

👍 +1

Document picture-in-picture (#260)

👍 +1

text-wrap-style (#259)

👍 +1

Scroll snap events (#255)

👍 +1

Scheduler API (#254)

👍 +1

interpolate-size (#253)

👍 +1

<img sizes="auto" loading="lazy"> (#250)

👍 +1

showPicker() for <select> (#226)

👍 +1

text-wrap: pretty (#212)

👍 +1

overlay (#211)

👍 +1

margin-trim (#201)

👍 +1

Container style queries (#196)

👍 +1

Navigation API (#172)

👍 +1

image-rendering: smooth (#154)

👍 +1

JavaScript modules in service workers (#143)

👍 +1

Picture-in-picture (video) (#90)

👍 +1

Shared worker (#19)

👍 +1


Activity since 2026-01-15