blog: This month in Servo (September 2025)

_posts/2025-10-18-this-month-in-servo.md

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+---
+layout:     post
+tags:       blog
+title:      "This month in Servo: and more!"
+date:       2025-10-18
+summary:    ao!! wrrrrao!!
+categories:
+---
+
+September was another busy month for Servo, with a bunch of new features in our nightly builds and [**our very first versioned release**]({{ '/blog/2025/10/20/servo-0.0.1-release/' | url }}):
+
+- the **Trusted Types** API is now stable (@TimvdLippe, #39281)
+- **strokeText()** on CanvasRenderingContext2D (@sagudev, #39183)
+- **invertSelf()** on DOMMatrix (@lumiscosity, #39148)
+- **getType()** and **supports()** on ClipboardItem (@Gae24, #39296)
+- **scrollParent** property on HTMLElement (@mrobinson, @Loirooriol, #39110)
+- **sizes** property on HTMLImageElement (@tharkum, #39466)
+
+**Viewport meta** tags are now enabled on mobile devices only, fixing a bug where they were enabled on desktop (@shubhamg13, #39133).
+You can still enable them if needed with `--pref viewport_meta_enabled` (@shubhamg13, #39207).
+
+The **scrollIntoView()** method on Element now works with shadow DOM (@mrobinson, @Loirooriol, #39144), and recurses to parent iframes if they are same origin (@Loirooriol, @mrobinson, #39475, #39397, #39153).
+
+Servo now supports **‘[Content-Encoding](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Encoding): [zstd](https://en.wikipedia.org/wiki/Zstd)’** (@webbeef, #36530), and we’ve fixed a bug causing spurious credentials prompts when a HTTP 401 has no ‘WWW-Authenticate’ header (@simonwuelker, #39215).
+We’ve also made a bunch of progress on **AbortController** (@TimvdLippe, #39290, #39295, #39374, #39406) and **<link rel=preload>** (@TimvdLippe, @jdm, #39033, #39034, #39052).
+
+Several types of **DOM exceptions can now have error messages** (@arihant2math, @rodio, @excitablesnowball, #39056, #39394, #39535), and we’ve also fixed a bug where links often need to be clicked twice (@yezhizhen, #39326), and fixed bugs affecting <img> attribute changes (@tharkum, #39483), the ‘:defined’ selector (@mukilan, #39325, #39390), invertSelf() on DOMMatrix (@lumiscosity, #39113), and the ‘href’ setter on Location (@arihant2math, @sagudev, #39051).
+
+One complex part of Servo isn’t even written in Rust, it’s written in Python!
+[**codegen.py**](https://github.com/servo/servo/blob/25d3c5a157e781db8813071a5ba647463546d0cd/components/script_bindings/codegen/codegen.py), which describes how to generate Rust code with bindings for every known DOM interface from the WebIDL, is now **fully type annotated** (@jerensl, @mukilan, #39070).
+
+## Embedding and automation
+
+Servo now requires **Rust 1.86** to build (@sagudev, #39185).
+
+**Keyboard scrolling** is now automatically implemented by Servo (@delan, @mrobinson, #39371, #39469), so embedders [no longer](https://github.com/servo/servo/pull/39371/files#diff-24ced12025398fd76b233d19f4507362ae8b3848157577d8041effc4c4a229ae) need to translate **arrow keys**, **Home**, **End**, **Page Up**, and **Page Down** to WebView API calls.
+This change also improves the behaviour of those keys, scrolling the element or <iframe> that was focused or most recently clicked (or a nearby ancestor).
+
+<code>[DebugOptions](https://doc.servo.org/servo_config/opts/struct.DebugOptions.html)::convert_mouse_to_touch</code> (`-Z convert-mouse-to-touch`) has been removed (@mrobinson, #39352), with no replacement.
+Touch event simulation continues to be available in servoshell as `--simulate-touch-events`.
+
+<code>[DebugOptions](https://doc.servo.org/servo_config/opts/struct.DebugOptions.html)::webrender_stats</code> (`-Z wr-stats` in servoshell) has been removed (@mrobinson, #39331); instead call <code>[toggle_webrender_debugging](https://doc.servo.org/servo/struct.WebView.html#method.toggle_webrender_debugging)([Profiler](https://doc.servo.org/servo/enum.WebRenderDebugOption.html#variant.Profiler))</code> on a WebView (or press **Ctrl**+**F12** in servoshell).
+
+<code>[DebugOptions](https://doc.servo.org/servo_config/opts/struct.DebugOptions.html)::trace_layout</code> (`-Z trace-layout`) has been removed (@mrobinson, #39332), since it had no effect.
+
+We’ve improved the docs for <code>[WebViewDelegate](https://doc.servo.org/servo/trait.WebViewDelegate.html)::[notify_history_changed](https://doc.servo.org/servo/trait.WebViewDelegate.html#method.notify_history_changed)</code> (@Narfinger, @mrobinson, @yezhizhen, #39134).
+
+When automating servoshell with **WebDriver**, commands **targeting elements** now correctly **scroll into view** if needed (@PotatoCP, @yezhizhen, #38508, #39265), allowing **Element Click**, **Element Send Keys**, **Element Clear**, and **Take Element Screenshot** to work properly when the element is outside the viewport.
+
+**WebDriver mouse inputs** now work correctly with **HiDPI scaling** on more platforms (@mrobinson, #39472), and we’ve improved the reliability of **Take Screenshot**, **Take Element Screenshot** (@yezhizhen, #39499, #39539, #39543), **Switch To Frame** (@yezhizhen, #39086), **Switch To Window** (@yezhizhen, #39241), and **New Session** (@yezhizhen, #39040).
+
+These improvements have enabled us to run the **WebDriver conformance tests** in CI by default (@PotatoCP, #39087), and also mean we’re closer than ever to running [WebDriver-based Web Platform Tests](https://web-platform-tests.org/writing-tests/testdriver.html).
+
+## servoshell
+
+You can now **enable experimental web platform features** with the click of a button (@jdm, #39125), instead of passing the command line option.
+
+**Favicons** now update correctly when you **navigate back and forward** (@webbeef, #39575), not just when you load a new page.
+
+servoshell’s **command line argument parsing** has been reworked (@Narfinger, #37194, #39316), which should fix the confusing behaviour of some options.
+
+On mobile devices, servoshell now resizes the webview correctly when the available space changes (@blueguy1, @yjx, @yezhizhen, #39507).
+
+On macOS, telling servoshell to [**take a screenshot**](https://w3c.github.io/webdriver/#screen-capture) no longer hides the window (@mrobinson, #39500).
+This does not affect taking a screenshot in headless mode (`--headless`), where there continues to be no window at all.
+
+## Performance
+
+Servo currently runs in **single-process mode** unless you opt in to `--multiprocess` mode, and we’ve landed a few perf improvements in that default mode.
+For one, in single-process mode, script can now **communicate with the embedder directly** for reduced latency (@jschwe, #39039).
+We also create one thread pool for the image cache now, rather than one pool per origin (@rodio, #38783).
+
+Many components of Servo that *would* be [separated by a process boundary](https://book.servo.org/architecture/overview.html#architecture) in multiprocess mode, now use [crossbeam channels](https://docs.rs/crossbeam-channel/0.5.15/crossbeam_channel/) in single-process mode, rather than using [IPC channels](https://docs.rs/ipc-channel/0.20.2/ipc_channel/) in both modes (@jschwe, #39073, #39076, #39345, #39347, #39348).
+[IPC channels](https://docs.rs/ipc-channel/0.20.2/ipc_channel/) are required when communicating with another process, but they’re more expensive, because they require serialising and deserialising each message, plus resources from the operating system.
+
+We’ve started working on an optimisation for string handling in Servo’s DOM layer (@Narfinger, #39480, #39481, #39504).
+Strings in our DOM have historically been represented as [ordinary Rust strings](https://doc.rust-lang.org/std/string/struct.String.html), but they often come from SpiderMonkey, where they use [a variety of representations](https://searchfox.org/firefox-main/rev/8e5d58cfed616cb90586c614e53d8ab1ffc8af27/js/src/vm/StringType.h#83), none of which are entirely compatible.
+SpiderMonkey strings would continue to need conversion to Servo strings, but the idea we’re working towards is to **make the conversion lazy**, in the hope that many strings will never end up being converted at all.
+
+We now use a faster hash algorithm for internal hashmaps that are not security-critical (@Narfinger, #39106, #39166, #39202, #39233, #39244).
+These changes also switch that faster algorithm from [FNV](https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function) to an [even simpler polynomial hash](https://docs.rs/rustc-hash/2.1.1/rustc_hash/), following in the footsteps of [Rust](https://github.com/rust-lang/rust/pull/37229) and [Stylo](https://bugzilla.mozilla.org/show_bug.cgi?id=1477628).
+
+We’ve also landed a few more self-contained perf improvements:
+- speeding up accesses to the event loop (@Narfinger, #39274, #39275)
+- reducing memory usage (@ritoban23, #39351)
+- reducing binary size (@lumiscosity, @Narfinger, #39437, #39567)
+
+## Donations
+
+Thanks again for your generous support!
+We are now receiving **???? USD/month** (+??.?% over August) in recurring donations.
+
+Historically this has helped cover the cost of our [speedy](https://ci0.servo.org) [CI](https://ci1.servo.org) [servers](https://ci2.servo.org) and [Outreachy interns](https://www.outreachy.org/alums/2025-06/#:~:text=Servo).
+Thanks to your support, we’re now setting up **[two](https://ci3.servo.org) [new](https://ci4.servo.org) CI servers for benchmarking**, and **[funding the work of our long-time maintainer]({{ '/blog/2025/09/17/your-donations-at-work-funding-jdm/' | url }}) Josh Matthews** (@jdm), with a particular focus on helping more people contribute to Servo.
+
+Keep an eye out for [further CI improvements](https://github.com/servo/servo/issues/38141) in the coming months, including [**ten-minute WPT builds**](https://github.com/servo/ci-runners/issues/21), **macOS arm64 builds**, and **faster pull request checks**.
+
+Servo is also on [thanks.dev](https://thanks.dev), and already **?? GitHub users** (±? from August) that depend on Servo are sponsoring us there.
+If you use Servo libraries like [url](https://crates.io/crates/url/reverse_dependencies), [html5ever](https://crates.io/crates/html5ever/reverse_dependencies), [selectors](https://crates.io/crates/selectors/reverse_dependencies), or [cssparser](https://crates.io/crates/cssparser/reverse_dependencies), signing up for [thanks.dev](https://thanks.dev) could be a good way for you (or your employer) to give back to the community.
+
+<figure class="_fig" style="width: 100%; margin: 1em 0;"><div class="_flex" style="height: calc(1lh + 3em); flex-flow: column nowrap; text-align: left;">
+    <div style="position: relative; text-align: right;">
+        <div style="position: absolute; margin-left: calc(100% * 5552 / 10000); padding-left: 0.5em;"><strong>5552</strong> USD/month</div>
+        <div style="position: absolute; margin-left: calc(100% * 5552 / 10000); height: calc(1lh + 1.5em); border-left: 1px solid;"></div>
+        <div style="position: absolute; margin-left: calc(100% - 0.5em); height: calc(1lh + 1.5em); border-left: 1px solid;"></div>
+        <div style="padding-right: 1em;"><strong>10000</strong><!-- USD/month --></div>
+    </div>
+    <progress value="5552" max="10000" style="transform: scale(3); transform-origin: top left; width: calc(100% / 3);"></progress>
+</div></figure>
+
+As always, use of these funds will be decided transparently in the Technical Steering Committee.
+For more details, head to our [Sponsorship page]({{ '/sponsorship/' | url }}).
+
+<style>
+    ._correction {
+        max-width: 33em;
+        margin: 1em auto;
+        border-bottom: 1px solid;
+        padding-bottom: 1em;
+    }
+    ._note {
+        margin: 1em 1em;
+        border-left: 1px solid;
+        padding-left: 1em;
+        opacity: 0.75;
+    }
+</style>