svelte

Commit Graph

Author	SHA1	Message	Date
Rich Harris	73f452fbc4	Merge branch 'main' into incremental-batches	3 days ago
Rich Harris	e027d8bf22	chore: annotate `each_array` return value (#18325 ) tiny self-mergeable change extracted from #18035 — just turns `each_array` from a `Derived<any[]>` to a `Derived<V[]>`	3 days ago
github-actions[bot]	70afafe18e	Version Packages (#18315 ) This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.56.0 ### Minor Changes - feat: allow declarations in the template ([#18282](https://github.com/sveltejs/svelte/pull/18282)) ### Patch Changes - perf: use `createElement` instead of `createElementNS` for HTML elements ([#18262](https://github.com/sveltejs/svelte/pull/18262)) - perf: store `current_sources` as a `Set` for O(1) membership checks ([#18278](https://github.com/sveltejs/svelte/pull/18278)) - perf: deduplicate identical hoisted templates within a component ([#18320](https://github.com/sveltejs/svelte/pull/18320)) - perf: hoist `rest_props` exclude list as a module-scope `Set` ([#18252](https://github.com/sveltejs/svelte/pull/18252)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	3 days ago
Rich Harris	1065572c41	Merge branch 'main' into incremental-batches	3 days ago
Rich Harris	6d26dce265	allow class/function expressions in tags (#18324 ) We shouldn't error on encountering `class` and `function`, because they are treated as expressions rather than declarations	3 days ago
7nik	6a955758a6	docs: mention since version of delcaration tags (#18322 )	3 days ago
Mathias Picker	2fae91af6d	perf: deduplicate identical hoisted templates within a component (#18320 ) Byte-identical templates hoisted from different fragments, elements, or branches now share a single `$.from_html` factory instead of each emitting its own module-scope variable - this shrinks generated output and avoids redundant runtime template parsing. Dedup is keyed on `(content, flags)` and is skipped in dev mode (templates there are wrapped in `$.add_locations`, which embeds per-call-site info). ### Before submitting the PR, please make sure you do the following - [ ] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [x] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Co-authored-by: Rich Harris <rich.harris@vercel.com>	3 days ago
Mathias Picker	a40c745fd9	perf: hoist rest_props exclude list as a module-scope Set (#18252 ) The compiler emitted an inline string array as the second argument to `$.rest_props(...)`, and the runtime did a linear `Array.prototype.includes` on it on every property access via the rest-props Proxy. The exclude list only depends on the component definition, not on the instance, so it can be hoisted to module scope and shared by every instance. Switching it to a `Set` at the same time makes each lookup O(1). For a component like `<Button ...rest />` rendered N times, this turns one per-instance allocation (plus a linear search on every rest-prop access) into one module-scope allocation plus O(1) lookups. The legacy `$$restProps` path is unchanged — it mutates the exclude list in its `deleteProperty` trap, so it can't share a hoisted Set across instances. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	3 days ago
Simon H	980c7e2321	fix: don't error on `{type}` in declaration tags (#18321 ) The `\b` in the regex matched on `}`, too, so you would get a very confusing "invalid declaration tag" error on `{type}`. Match on whitespace instead (because that's what has to come afterwards) --------- Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com> Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: Rich-Harris <hello@rich-harris.dev>	3 days ago
Rich Harris	5300843e86	chore: bump playwright (#18319 ) hopefully this will fix the CI timeouts	4 days ago
Simon H	59d3a36f82	feat: allow declarations in the template (#18282 ) Allows `{let/const ...}` declarations in all places (and more) where we already allow `{@const ...}` (which will eventually get deprecated in favor of this new feature). Closes: #16490 Companion PRs: - https://github.com/sveltejs/language-tools/pull/3033 - https://github.com/sveltejs/prettier-plugin-svelte/pull/533 - https://github.com/sveltejs/eslint-plugin-svelte/pull/1533 - https://github.com/sveltejs/svelte-eslint-parser/pull/891 --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	4 days ago
Rich Harris	656dae6780	chore: try and discourage slop, even a tiny bit (#18293 ) i don't know how to stem the flood of slop PRs but maybe this will help a tiny bit --------- Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>	4 days ago
Rich Harris	3fad9cf838	chore: fix browser-support regression check (#18316 ) vercel bot caught this in the release PR https://github.com/sveltejs/svelte/pull/18315#pullrequestreview-4383622174	4 days ago
Rich Harris	a9e82dd388	chore: remove `on_fork_commit` (#18318 ) Simon thinks it was because he thought that committing the fork != committing the batch, and that this could result in an error boundary showing up too late. But that's not the case	4 days ago
Rich Harris	47a4dd3712	tweak	4 days ago
Rich Harris	6bba647073	working?	4 days ago
Rich Harris	e413dbf668	Merge branch 'main' into incremental-batches	4 days ago
Mathias Picker	a9916053d9	perf: use createElement instead of createElementNS for HTML elements (#18262 ) ## Summary The current wrapper always calls `document.createElementNS(namespace ?? NAMESPACE_HTML, tag, options)` — even for HTML elements (the >99% case), and even when `options` would be `undefined`. Two effects compound: 1. Route HTML elements through `createElement` — Blink has a fast path that skips the namespace lookup `createElementNS` always performs. 2. Omit the trailing `undefined` argument — V8/Blink take a slower path for `createElementNS(ns, tag, undefined)` (and `createElement(tag, undefined)`) than for the bare 2-arg form. This applies symmetrically to the SVG/MathML branch, where the wrapper now also avoids the `undefined` 3rd arg. The wrapper dispatches to the fastest call shape for every input — `{HTML, non-HTML}` × `{with is, without is}` × no `undefined` ever. ## Affects Every place Svelte constructs a DOM element internally: `<svelte:element>`, `run_scripts`, the per-component `<style>` injector, the `{@html}` wrapper, and the `<template>` element used to clone string templates. ## Numbers Measured in headless Chromium (Chromium 145) using the browser bench harness from #18261, 2–3 runs, median. Lower per-call is better; higher hz is better. ### Raw call shapes (what each shape costs in the browser) \| \| hz \| per-call \| \| ------------------------------------------- \| -------: \| -------: \| \| `createElement(tag)` \| ~1,210k \| ~0.83 µs \| \| `createElement(tag, undefined)` \| ~901k \| ~1.11 µs \| \| `createElementNS(NS_HTML, tag)` \| ~913k \| ~1.10 µs \| \| `createElementNS(NS_HTML, tag, undefined)` \| ~630k \| ~1.59 µs \| \| `createElement(tag, { is })` \| ~484k \| ~2.07 µs \| \| `createElementNS(SVG_NS, tag)` \| ~333k \| ~3.01 µs \| \| `createElementNS(SVG_NS, tag, undefined)` \| ~303k \| ~3.30 µs \| \| `createElementNS(SVG_NS, tag, { is })` \| ~245k \| ~4.08 µs \| Two stable effects fall out: - Trailing `undefined` is consistently slower than the bare form — ~26% on `createElement`, ~31% on `createElementNS` (HTML), ~10% on `createElementNS` (SVG). - `createElement` skips a namespace lookup that `createElementNS` always performs — ~32% delta for equal-shape calls (`createElement(tag)` vs `createElementNS(NS_HTML, tag)`). ### Per-case impact of this PR \| Case (namespace, `is`) \| Old wrapper call \| Old hz \| New wrapper call \| New hz \| Speedup \| \| ----------------------------- \| --------------------------------------------- \| --------: \| ------------------------------ \| --------: \| ------: \| \| HTML, no `is` (dominant path) \| `createElementNS(NS_HTML, tag, undefined)` \| ~630k \| `createElement(tag)` \| ~1,210k \| ~92% (1.92×) \| \| HTML, with `is` \| `createElementNS(NS_HTML, tag, { is })` \| (slow) \| `createElement(tag, { is })` \| ~484k \| similar to above (just the NS-skip) \| \| SVG/MathML, no `is` \| `createElementNS(ns, tag, undefined)` \| ~303k \| `createElementNS(ns, tag)` \| ~333k \| ~10% \| \| SVG/MathML, with `is` \| `createElementNS(ns, tag, { is })` \| ~245k \| same \| ~245k \| no change \| No measurable change in JSDOM (both shapes route through the same JS implementation there). The headline gain — ~92% on the dominant HTML-no-`is` path — combines both effects roughly equally: dropping the `undefined` (~46%) and switching to `createElement` (~32%). Wrapper-vs-raw was also verified: the new wrapper measured to within ±2% of raw `document.createElement(tag)` for the HTML-no-`is` case, so the function-call indirection adds no measurable overhead. See #18261 for the benchmark and methodology. ## Test plan - [x] All 5881 runtime tests still pass (runtime-runes + runtime-legacy) - [x] `<svelte:element xmlns={null}>` correctly falls back to HTML (covered by existing `dynamic-element-dynamic-namespace` test) - [x] SVG/MathML namespaces still go through `createElementNS` - [x] Custom-element `is` option still honoured on both branches 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>	5 days ago
Mathias Picker	27e74c4df7	docs: add auto-generated browser support page (#18276 ) ## Summary Adds a [Browser support](https://github.com/MathiasWP/svelte/blob/document-pipeline-draft/documentation/docs/07-misc/05-browser-support.md) page listing the minimum browser versions Svelte's runtime and compiler output require. The page (headline floor + per-feature requirements) is auto-generated by `packages/svelte/scripts/generate-browser-support.js`, which scans the code Svelte actually ships against the [web-features](https://github.com/web-platform-dx/web-features) Baseline dataset and resolves results to concrete browser versions via [baseline-browser-mapping](https://github.com/web-platform-dx/baseline-browser-mapping). CI fails if a PR moves the floor without regenerating the page. For 5.55.9 the floor is Baseline 2020: Chrome/Edge 87, Firefox 83, Safari 14. ## How it works 1. Headline floor. Each runtime entry from `pkg.exports` is bundled with rollup using production conditions, then walked with TypeScript's compiler API + TypeChecker. The walker (`browser-support.detector.js`) flags any web-features ID the runtime references; the highest Baseline year among them is the floor. 2. Per-feature requirements. Every user-facing surface is enumerated programmatically — every `bind:` from `binding_properties`, every public subpackage export discovered via `pkg.exports` + `import as ns`, every rune from `RUNES`, and directives (`transition:` / `animate:` / `use:` / `@attach` / `{@html}` / custom elements). Each gets a fixture, compiled and bundled like user code, then scanned. A row appears only when the fixture's floor exceeds the runtime floor. 3. Supplemental rules. A handful of APIs `web-features` doesn't catalogue (`getComputedStyle(...).zoom`, `box: 'device-pixel-content-box'`) are detected with the same type-aware walker via a small `register_extra_rules` list with inline justifications. 4. Ignore sets. `SAFE_TO_IGNORE` covers dataset bugs and feature-detected APIs with graceful fallbacks. `BEHAVIORAL_IGNORE` hides APIs reached only via specific user code from the headline (they still surface as conditional rows); staleness-checked, so CI fails if an entry no longer exists in the runtime. Resolves #18198. Provides an answer to the long-standing #558. ## Test plan - [ ] \`pnpm --filter svelte generate:browser-support\` regenerates the page idempotently - [ ] CI fails when a code change bumps the floor without regenerating the page - [ ] Page renders correctly on svelte.dev 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com> Co-authored-by: Rich Harris <rich.harris@vercel.com>	5 days ago
Rich Harris	8185ce8111	merge main	5 days ago
Mathias Picker	67090e8ee8	perf: store current_sources as Set for O(1) membership checks (#18278 ) `current_sources` tracks the sources created within the active reaction so that reading or writing them during that same reaction doesn't trigger a re-run. It was an `Array` checked with `Array.prototype.includes.call(...)` in three hot places: the `state_unsafe_mutation` guard, `set()`'s destruction check, and `schedule_possible_effect_self_invalidation`. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	5 days ago
github-actions[bot]	0bb715d3cf	Version Packages (#18255 ) This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.55.10 ### Patch Changes - fix: unlink errored and otherwise finished batch ([#18264](https://github.com/sveltejs/svelte/pull/18264)) - perf: walk composedPath() directly in delegated event propagation ([#18268](https://github.com/sveltejs/svelte/pull/18268)) - fix: transfer effects when merging batches ([#18254](https://github.com/sveltejs/svelte/pull/18254)) - fix: allow `$derived(await ...)` in disconnected effect roots ([#18273](https://github.com/sveltejs/svelte/pull/18273)) - fix: remove temporary raw-text hydration markers ([#18269](https://github.com/sveltejs/svelte/pull/18269)) - fix: propagate async `@const` blockers through closure references so template expressions like `{(() => host)()}` correctly wait for the awaited value ([#18309](https://github.com/sveltejs/svelte/pull/18309)) - fix: properly unlink batches ([#18298](https://github.com/sveltejs/svelte/pull/18298)) - fix: settle discarded batch ([#18290](https://github.com/sveltejs/svelte/pull/18290)) - fix: declare `let:` directives before `{@const}` declarations on slotted elements ([#18271](https://github.com/sveltejs/svelte/pull/18271)) - fix: resume outro-ed branches if they were kept around ([#18291](https://github.com/sveltejs/svelte/pull/18291)) - fix: avoid waterfall-warning when async resolves to same value ([#18297](https://github.com/sveltejs/svelte/pull/18297)) - fix: correctly coordinate component-level effects inside async blocks ([#18260](https://github.com/sveltejs/svelte/pull/18260)) - fix: make unnecessary commit work less likely ([#18263](https://github.com/sveltejs/svelte/pull/18263)) - chore: add tag name to `a11y_click_events_have_key_events` warning ([#18272](https://github.com/sveltejs/svelte/pull/18272)) - fix: catch rejected promises while merging/committing ([#18266](https://github.com/sveltejs/svelte/pull/18266)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	5 days ago
Rich Harris	688671ec23	chore: fix printing in sandbox (#18311 ) when `PRINT` is true, the sandbox should write out the printed code. at present it doesn't do this if `AST` is not also true	5 days ago
Simon H	4953860835	chore: remove unused class property (#18307 ) remnant of blocker approach	5 days ago
Simon H	638ab370a5	fix: prevent batch unlinking twice (#18303 ) Merged #18298 a bit too soon - there's still a situation which can corrput the linked list: If we merge one batch into another, it will unlink the batch immediately. But `discard` also calls it, running the unlink logic again, which can corrupt the linked list. Sketch: 1. Batch A is pending. 2. Batch B starts later, intersects A, resolves first, and merges into A. 3. B is unlinked immediately, but `A.oncommit(() => B.discard())` remains. 4. Independent batch C is created while A is still pending and is linked after A. 5. A commits, calls `B.discard()`, and B's stale `#prev`/`#next` can set `A.#next = null` / `last_batch = A`, disconnecting C. Not able to produce a failing test from it but it's definitely a fix we need to make. Also moved `#link` into a constructor, because it is (and should be) used only once. Also made the action after an error `discard` instead of just `#unlink` because this batch is done for and e.g. pending `settled` should resolve, too.	5 days ago
Rich Harris	0da9f9e2ab	fix: disallow effect creation after `await` (#18299 ) We incorrectly restore effect context after an`$derived(await ...)` if it occurs inside an async function, but only for those, no other `await` expressions. This is buggy and wrong. We only want to restore context _inside_ an async derived expression (including template expressions)` so that `await a + b` works correctly. It's possible that this will be a breaking change (albeit not semver-violating, because `experimental`) for some people if they are creating effects after an `await` (other than at the top level of a component). This is regrettable, but it should never have worked in the first place.	5 days ago
Simon H	d4be4e2973	chore: ensure treeshaking test runs during CI (#18302 ) Would've caught the regression in #18250 - without this the tests were all green, giving a false sense of "this is correct"	6 days ago
Elliott Johnson	e705369dee	fix: propagate async @const blockers through closure references (#18309 ) Right now, if you have the following: ```svelte {@const data = await foo} <p>{(() => data)()}<p> ``` It will blow up during CSR, because it tries to read `data` before it exists. The solution to this is to consider references inside closures as blockers for those closures. This _does_ mean we'll overblock in some circumstances, such as: ```svelte {@const data = await foo} <button onclick={() => data}>foo<button> ``` But I wonder if that's actually incorrect? If the user were to click `onclick` before `data` is ready, it would blow up. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	6 days ago
Rich Harris	ec08dbc7ee	fix: only unlink batch if we're done with it (#18298 ) alternative to #18296 — no need to make batches relinkable if we only unlink them when we're fully done with them	6 days ago
Simon H	b40c359d44	fix: don't assume boundary exists during increment/decrement (#18289 ) Follow-up to #18273 (not merged yet hence no changeset here): We can run into a null-pointer when wanting to increment/decrement inside an effect root that is outside a the component tree. Similarly, if not using the component logic to unset context at the right time we gotta do it "manually" inside `save`. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com> Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>	6 days ago
Simon H	c01e598fff	fix: avoid waterfall-warning when async resolves to same value (#18297 )	6 days ago
Rich Harris	070a0c4f77	Revert "perf: use Set instead of Array for constant lookups in utils.js" (#18294 ) Reverts sveltejs/svelte#18250	6 days ago
Rich Harris	9ff512377e	gate on non-async mode	6 days ago
Rich Harris	2f4b0584fa	fix	7 days ago
Rich Harris	e5f77acab5	Merge branch 'main' into incremental-batches	7 days ago
Rich Harris	c9f7298270	chore: fix spelling in test (#18292 ) ugh i forgot to approve workflows in slop PR #18281 and now tests are failing	7 days ago
RonGamzu	d2c7fa3494	fix: use consistent spelling in script_unknown_attribute warning (#18281 ) ## Summary The `script_unknown_attribute` warning message used American English (`Unrecognized`) while every other user-facing error/warning in the compiler uses British English (`Unrecognised`): - `options_unrecognised` error: `Unrecognised compiler option…` - `unknown_code` warning: `is not a recognised code` This change updates `script_unknown_attribute` to match, then regenerates `warnings.js` and the reference documentation from the source message file via `node scripts/process-messages`. ## Test plan - Spelling change is isolated to the `script_unknown_attribute` warning message - `warnings.js` and generated docs were updated by running `node scripts/process-messages` - All three occurrences (source, generated JS, generated docs) are consistent	7 days ago
Simon H	60eaa92b0b	fix: resume outro-ed branches if they were kept around (#18291 ) If a branch is removed from the visible dom, it may be kept around because a subsequent batch will intro it again. If we don't resume the effects it will stay inert and therefore not react to updates anymore	7 days ago
Simon H	871e590c59	fix: settle discarded batch (#18290 ) Without this the promise would never resolve	7 days ago
Mathias Picker	e6110d31c5	perf: use Set instead of Array for constant lookups in utils.js (#18250 ) Several constant lookup tables in `utils.js` were arrays searched with `Array.prototype.includes`, which is O(n). They're queried often — per attribute during attribute setup and SSR, per event during event delegation, and per identifier during compilation. Switching them to `Set` makes each lookup O(1) without changing any public behaviour.	7 days ago
Rich Harris	8332bb32a2	fixes	1 week ago
Rich Harris	6d835a00fb	fix. almost there	1 week ago
Rich Harris	96e6b1a71e	Merge branch 'main' into incremental-batches	2 weeks ago
Simon H	fe9ab936b6	fix: allow `$derived(await ...)` in disconnected effect roots (#18273 ) If `$effect.root` is created outside the component tree, the boundary property is null Fixes #18188	2 weeks ago
Karl Georgsen	f023e8d7c8	chore: add tag name to a11y_click_events_have_key_events warning (#18272 ) Ref: https://github.com/sveltejs/svelte/issues/15100 Adds the tag name to the `a11y_click_events_have_key_events` warning given when a non-interactive element has a click handler but no keyboard events. This already happens in `a11y_no_static_element_interactions`, and should probably happen in many more messages.	2 weeks ago
wheelman	bb69f9c44c	fix: declare `let:` directives before `{@const}` on slotted elements (#18271 ) Fixes #18119 (missed a spot in #16985)	2 weeks ago
Rich Harris	43f549c798	merge	2 weeks ago
Rich Harris	957dbfe75a	drive-by	2 weeks ago
Rich Harris	d1de7c5b03	fix	2 weeks ago
Puneet Dixit	8b961be0b1	fix: remove raw-text hydration markers (#18269 ) Fixes #14413. This keeps the temporary raw-text hydration sentinel used by dynamic `<svelte:element>` from becoming part of the final DOM. Hydration still gets a marker to advance through for raw-text children, but the marker is removed after the child renderer runs, so `<style>` and `<script>` contents stay identical to SSR output. Tests: - `pnpm test hydration -t svelte-head-dynamic-style` - `pnpm test hydration` - `pnpm test runtime-runes -t svelte-element` - `pnpm lint` - `git diff --check` --------- Co-authored-by: Puneet Dixit <236133619+puneetdixit200@users.noreply.github.com> Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>	2 weeks ago

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