--- title: This Month in Ladybird | daily.dev description: Ladybird's April progress report covers 288 merged PRs from 36 contributors, with 17,214 new passing Web Platform Tests bringing the total to 1,799,262.... canonical: https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: This Month in Ladybird | daily.dev og:description: Ladybird's April progress report covers 288 merged PRs from 36 contributors, with 17,214 new passing Web Platform Tests bringing the total to 1,799,262.... og:url: https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn og:image: https://api.daily.dev/og/posts/VO7h6anwN.png og:image:alt: This Month in Ladybird og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # This Month in Ladybird **[Ladybird Browser](https://daily.dev/sources/ladybird)** · 8 min read · 0 upvotes · 0 comments ## Summary Ladybird's April progress report covers 288 merged PRs from 36 contributors, with 17,214 new passing Web Platform Tests bringing the total to 1,799,262. Performance work boosted Speedometer 2 scores by 47% and Speedometer 3 by 38%, driven by faster JavaScript function calls via a redesigned stack frame layout, flexbox layout optimizations skipping expensive automatic minimum size calculations, and RegExp engine optimizations yielding up to 16x speedups. Other additions include script-blocking style sheet handling per the HTML spec, dialog ::backdrop pseudo-elements, improved scrollbar interactions, refactored CSS descriptor parsing, corrected CSS URL resolution timing, refined Streams API piping, better float/clear handling, more than doubled IndexedDB WPT pass rate, a new URLPattern implementation, and support for the moveBefore() DOM API for atomic node moves. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is the moveBefore() DOM API and how is it different from insertBefore()? moveBefore() is a DOM API that reparents or reorders nodes as an atomic move, preserving state that insertBefore() would destroy. Unlike insertBefore(), which implicitly removes and re-inserts a node (triggering removal and insertion side effects), moveBefore() avoids running those steps, preventing iframe reloads, preserving active selections or focused form controls, popover open/close state, and animation state. Ladybird added support for this API. _Track new DOM APIs like moveBefore() as browsers adopt them by following browser engine updates on daily.dev._ ### How much did Ladybird improve its Speedometer benchmark scores through performance work? Ladybird improved its Speedometer 2 score by 47% and its Speedometer 3 score by 38% in a single month of optimization work. Gains came from faster JavaScript function calls (single stack allocation instead of multiple heap allocations, a new argument operand type in the bytecode ISA), flexbox layout optimizations that skip unnecessary intrinsic size calculations, and RegExp engine optimizations delivering up to 16x speedups in some cases. _Developers evaluating browser engine performance trends can follow benchmark progress like this on daily.dev._ ### What is URLPattern and which web specifications use it? URLPattern is a web platform primitive for declarative URL matching using a pattern syntax based on the path-to-regexp library. It is used by several emerging web specifications, including the Service Worker Static Routing API, the Use-As-Dictionary HTTP header, and the Speculation Rules API. Ladybird implemented URLPattern support this month. _Keep up with new web platform primitives like URLPattern as browser support lands via daily.dev._ --- Tags: [#javascript](https://daily.dev/tags/javascript), [#css](https://daily.dev/tags/css) [View this post on daily.dev](https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"This Month in Ladybird","url":"https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn"},"datePublished":"2026-08-31T05:54:40.705Z","dateModified":"2026-08-31T05:55:31.737Z","description":"Ladybird's April progress report covers 288 merged PRs from 36 contributors, with 17,214 new passing Web Platform Tests bringing the total to 1,799,262....","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/f0d04d597be9efdaf11883698ad30378?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/f0d04d597be9efdaf11883698ad30378?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Ladybird Browser","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Ladybird Browser","logo":"https://media.daily.dev/image/upload/s--gBOjamNh--/f_auto,q_auto/v1788155675/logos/ladybird?_a=BAMAMicg0","url":"https://daily.dev/sources/ladybird"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"javascript,css","timeRequired":"PT8M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Ladybird Browser","item":"https://daily.dev/sources/ladybird"},{"@type":"ListItem","position":3,"name":"This Month in Ladybird"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/this-month-in-ladybird-vo7h6anwn#faq","mainEntity":[{"@type":"Question","name":"What is the moveBefore() DOM API and how is it different from insertBefore()?","acceptedAnswer":{"@type":"Answer","text":"moveBefore() is a DOM API that reparents or reorders nodes as an atomic move, preserving state that insertBefore() would destroy. 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