11040 Commits (2deebdea8ffbdb74790ce7021e3b6992b39b77bb)

 

All Branches   

Search

Author	SHA1	Message	Date
Simon H	2deebdea8f	fix: handle asnyc updates within pending boundary (#17873) ... When an async value is updated inside the boundary while the pending snippet is shown, we previously didn't notice that update and instead showed an outdated value once it resolved. This fixes that by rejecting all deferreds inside an async_derived while the pending snippet is shown. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	4 days ago
dev-miro26	0206a2019e	fix: clean up externally-added DOM nodes in {@html} on re-render (#17853) ... Fixes `{@html}` content duplication when used inside a contenteditable element. When `{@html content}` is inside a contenteditable element and the user types, the browser inserts DOM nodes directly into the {@html} managed region. On re-render (e.g. triggered by a blur handler setting `content = e.currentTarget.innerText`, the `{@html} `block only removed nodes it previously created via` effect.nodes`, leaving browser-inserted nodes in place. This caused content to appear twice — once as leftover text nodes and once as the new `{@html}` output. The fix tracks the boundary node (`previousSibling `of the anchor at init) and removes all nodes between the boundary and the anchor on re-render, ensuring externally-added nodes are also cleaned up. Closes: #16993 --------- Co-authored-by: 7nik <kfiiranet@gmail.com> Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>	4 days ago
Rich Harris	3df2645451	chore: deactivate batch after async derived resolves (#17865) ... Extracted from #17805. Similar to #17864, I'm not aware of any bugs resulting from this, but the fact that we're setting `current_batch` before calling `internal_set` and then not _unsetting_ `current_batch` feels like something that could potentially bite us.	5 days ago
Rich Harris	2a1f5ada13	perf: avoid re-traversing the effect tree after `$:` assignments (#17848) ... If an assignment happens in a `$:` statement, any affected effects are rescheduled while the traversal is ongoing. But this is wasteful — it results in the `flush_effects` loop running another time, even though the affected effects are guaranteed to be visited _later_ in the traversal (unless the thing being updated is a store). This PR fixes it: inside a `legacy_pre_effect`, we temporarily pretend that the branch _containing_ the component with the `$:` statement is the `active_effect`, such that Svelte understands that any marked effects are about to be visited and thus don't need to be scheduled. We deal with the store case by temporarily pretending that there _is_ no `active_effect`. I will be delighted when we can rip all this legacy stuff out of the codebase. ### Before submitting the PR, please make sure you do the following - [x] 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. - [ ] 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`	5 days ago
Rich Harris	7dc864d941	Revert "fix: skip derived re-evaluation inside inert effect blocks" (#17869) ... Reverts sveltejs/svelte#17852, because it isn't a real fix https://github.com/sveltejs/svelte/pull/17868	5 days ago
Rich Harris	aed36051fd	chore: robustify `flatten` (#17864) ... Extracted from #17805. Currently we restore context in`flatten` unnecessarily in the case where we have async expressions but no blockers (the context is already correct), and we don't unset context after blockers resolve in the case where we have them. The first bit is suboptimal, but the second bit feels bug-shaped, even though I'm not currently aware of any actual bugs that have resulted from this. ### Before submitting the PR, please make sure you do the following - [x] 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. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] 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`	6 days ago
Rich Harris	9066b75c01	chore: tidy up (#17863) ... small tweaks, will self-merge	6 days ago
dependabot[bot]	61a443f1fa	chore(deps): bump immutable from 4.3.7 to 4.3.8 (#17860) ... Bumps [immutable](https://github.com/immutable-js/immutable-js) from 4.3.7 to 4.3.8. <details> <summary>Release notes</summary> <p><em>Sourced from <a href="https://github.com/immutable-js/immutable-js/releases">immutable's releases</a>.</em></p> <blockquote> <h2>v4.3.8</h2> <p>Fix Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in immutable</p> </blockquote> </details> <details> <summary>Changelog</summary> <p><em>Sourced from <a href="https://github.com/immutable-js/immutable-js/blob/main/CHANGELOG.md">immutable's changelog</a>.</em></p> <blockquote> <h1>Changelog</h1> <p>All notable changes to this project will be documented in this file.</p> <p>The format is based on <a href="https://keepachangelog.com/en/1.0.0/">Keep a Changelog</a>, and this project adheres to <a href="https://semver.org/spec/v2.0.0.html">Semantic Versioning</a>. Dates are formatted as YYYY-MM-DD.</p> <h2>Unreleased</h2> <h2>5.1.5</h2> <ul> <li>Fix Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in immutable</li> </ul> <h2>5.1.4</h2> <ul> <li>Migrate some files to TS by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2125">immutable-js/immutable-js#2125</a> <ul> <li>Iterator.ts</li> <li>PairSorting.ts</li> <li>toJS.ts</li> <li>Math.ts</li> <li>Hash.ts</li> </ul> </li> <li>Extract CollectionHelperMethods and convert to TS by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2131">immutable-js/immutable-js#2131</a></li> <li>Use npm <a href="https://docs.npmjs.com/trusted-publishers">trusted publishing only</a> to avoid token stealing.</li> </ul> <h3>Documentation</h3> <ul> <li>Fix/a11y issues by <a href="https://github.com/lyannel"><code>@​lyannel</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2136">immutable-js/immutable-js#2136</a></li> <li>Doc add Map.get signature update by <a href="https://github.com/borracciaBlu"><code>@​borracciaBlu</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2138">immutable-js/immutable-js#2138</a></li> <li>fix(doc):minor-issues#2132 by <a href="https://github.com/JayMeDotDot"><code>@​JayMeDotDot</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2133">immutable-js/immutable-js#2133</a></li> <li>Fix algolia search by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2135">immutable-js/immutable-js#2135</a></li> <li>Typo in OrderedMap by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2144">immutable-js/immutable-js#2144</a></li> </ul> <h3>Internal</h3> <ul> <li>chore: Sort all imports and activate eslint import rule by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2119">immutable-js/immutable-js#2119</a></li> </ul> <h2>5.1.3</h2> <h3>TypeScript</h3> <ul> <li>fix: allow readonly map entry constructor by <a href="https://github.com/septs"><code>@​septs</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2123">immutable-js/immutable-js#2123</a></li> </ul> <h3>Documentation</h3> <p>There has been a huge amount of changes in the documentation, mainly migrate from an autogenerated documentation from .d.ts file, to a proper documentation in markdown. The playground has been included on nearly all method examples. We added a page about browser extensions too: <a href="https://immutable-js.com/browser-extension/">https://immutable-js.com/browser-extension/</a></p> <h3>Internal</h3> <!-- raw HTML omitted --> </blockquote> <p>... (truncated)</p> </details> <details> <summary>Commits</summary> <ul> <li><a href="485cbe0edf"><code>485cbe0</code></a> 4.3.8</li> <li><a href="6ed4eb6269"><code>6ed4eb6</code></a> Merge commit from fork</li> <li><a href="94bcd3c799"><code>94bcd3c</code></a> fix new proto key injection</li> <li><a href="faeb58b0cc"><code>faeb58b</code></a> fix Prototype Pollution in mergeDeep, toJS, etc.</li> <li>See full diff in <a href="https://github.com/immutable-js/immutable-js/compare/v4.3.7...v4.3.8">compare view</a></li> </ul> </details> <details> <summary>Maintainer changes</summary> <p>This version was pushed to npm by [GitHub Actions](<a href="https://www.npmjs.com/~GitHub">https://www.npmjs.com/~GitHub</a> Actions), a new releaser for immutable since your current version.</p> </details> <br /> [](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- <details> <summary>Dependabot commands and options</summary> <br /> You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself) You can disable automated security fix PRs for this repo from the [Security Alerts page](https://github.com/sveltejs/svelte/network/alerts). </details> Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	6 days ago
Rich Harris	e3f06f9fc7	fix: skip derived re-evaluation inside inert effect blocks (#17852) ... this is #17850 with changes (for whatever reason I wasn't able to push direct to the fork) — same test but simplified, and a simpler fix that doesn't undo the recent (necessary!) changes to the scheduling logic --------- Co-authored-by: Mattias Granlund <mtsgrd@gmail.com>	6 days ago
github-actions[bot]	25a1c5368b	Version Packages (#17842) ... 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@5.53.7 ### Patch Changes - fix: correctly add \_\_svelte_meta after else-if chains ([#17830](https://github.com/sveltejs/svelte/pull/17830)) - perf: cache element interactivity and source line splitting in compiler ([#17839](https://github.com/sveltejs/svelte/pull/17839)) - chore: avoid rescheduling effects during branch commit ([#17837](https://github.com/sveltejs/svelte/pull/17837)) - perf: optimize CSS selector pruning ([#17846](https://github.com/sveltejs/svelte/pull/17846)) - fix: preserve original boundary errors when keyed each rows are removed during async updates ([#17843](https://github.com/sveltejs/svelte/pull/17843)) - perf: avoid O(n²) name scanning in scope `generate` and `unique` ([#17844](https://github.com/sveltejs/svelte/pull/17844)) - fix: preserve each items that are needed by pending batches ([#17819](https://github.com/sveltejs/svelte/pull/17819)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	1 week ago
Philip Breuer	b7bc1309aa	fix: preserve original boundary errors when keyed each rows are removed during async updates (#17843) ... Fixes a runtime edge case where keyed #each reconciliation can hit a missing item during deferred async updates, causing an internal crash and masking the original boundary error. Fixes #17841 ### Before submitting the PR, please make sure you do the following - [x] 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 - [] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	1 week ago
Mathias Picker	0965028d3b	perf: optimize CSS selector pruning (#17846) ... ## Summary Reduces CSS selector pruning overhead by eliminating unnecessary allocations and redundant work in the hot path. **Changes:** - Replace `.slice()` + `.shift()`/`.pop()` in `apply_selector` with index-based `from`/`to` params — avoids O(n) array copies per recursive call - Merge `has_selectors`/`other_selectors` split in `relative_selector_might_apply_to_node` into a single pass — eliminates 2 temporary array allocations per call - Hoist `name.toLowerCase()` out of the inner loop in `attribute_matches` - Replace `value.split(/\s/).includes()` with `indexOf` + boundary checks in `test_attribute` for `~=` — avoids array allocation on every class match - Skip `name.replace()` regex when selector name has no backslash ## Benchmark Interleaved benchmark (5 rounds, alternating baseline/optimized): ``` --- Round 1 --- Baseline: min=59.58ms median=64.63ms Optimized: min=47.20ms median=54.35ms --- Round 2 --- Baseline: min=59.11ms median=64.90ms Optimized: min=48.36ms median=54.74ms --- Round 3 --- Baseline: min=58.38ms median=64.06ms Optimized: min=48.38ms median=53.83ms --- Round 4 --- Baseline: min=58.49ms median=63.99ms Optimized: min=48.45ms median=53.82ms --- Round 5 --- Baseline: min=58.40ms median=64.07ms Optimized: min=48.97ms median=54.64ms Best min: Before=58.38ms After=47.20ms Improvement=19.1% Best median: Before=63.99ms After=53.82ms Improvement=15.9% ``` CPU profile before → after: | Function | Before | After | |---|---|---| | `relative_selector_might_apply_to_node` | 14.3% | 5.2% | | `attribute_matches` | 4.0% | 3.3% | | `test_attribute` | 3.2% | <0.9% | ## Test plan - [x] All 196 CSS tests pass (180 samples + 16 parse) - [x] All 31 snapshot tests pass - [x] All 2380 runtime-runes tests pass - [x] All 3291 runtime-legacy tests pass - [x] All 145 compiler-errors tests pass - [x] All 326 validator tests pass - [x] Added `css-prune-edge-cases` test covering: `~=` word matching (substring vs whole word), deep combinator chains (4+ levels), `:has()` combined with class selectors, escaped selectors, `:is()`/`:where()`/`:not()` with combinators - [x] Edge case test passes on both baseline and optimized code 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com> Co-authored-by: Rich Harris <rich.harris@vercel.com>	1 week ago
Mathias Picker	32111f9e84	perf: avoid O(n²) name scanning in scope generate/unique (#17844) ... ## Summary `Scope.generate()` and `ScopeRoot.unique()` search for available names by iterating from suffix `_1` upward. When the same preferred name is generated many times (e.g. `text` is generated 482 times in a large component), the Nth call re-scans all N-1 already-taken names — O(n²) total work. This adds a `#name_counters` Map to `ScopeRoot` that tracks the next suffix to try per name, so each call resumes from where the last one left off. Generated names are identical to before. ## Benchmark (interleaved, best-of-3 rounds) | Component | Min | Median | |---|---|---| | Realistic (~80 lines) | ~1% | ~7% | | Medium (316 lines) | ~1% | ~5% | | Large (642 lines) | ~7% | ~2% | | XLarge (1302 lines) | **~11%** | **~10%** | ## Test plan - [x] All snapshot tests pass (name generation unchanged) - [x] All validator, compiler-error, runtime-runes, runtime-legacy tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	1 week ago
Rich Harris	2f12b60701	chore: avoid reschedule during branch commit (#17837) ... If a dirty effect is resumed — for example `condition` becomes `false` then `count` changes then `condition` becomes `true` again... ```svelte {#if condition} <div transition:fade> {count} </div> {/if} ``` ...then the effect is rescheduled. This happens when branches are committed (after the effect tree is traversed, before effects are flushed). That's undesirable, because it causes another turn of the `flush_effects` loop. It's better if we can handle everything in a single pass, which is what happens in this PR. The trade-off is that we have to traverse the entire effect tree, instead of skipping inert subtrees, which is a trade-off that I think makes sense. The real agenda here is that I'm trying to eliminate all `schedule_effect` calls that happen at inconvenient times, because I have a hunch that if we do that we can return to #17805, which I'm increasingly convinced will be important. (You might have to trust me on this; a full explanation would look a bit charlie-day-meme.jpg. Call it a hunch.) ### Before submitting the PR, please make sure you do the following - [x] 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. - [ ] 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: Vercel <vercel[bot]@users.noreply.github.com>	1 week ago
Rich Harris	00dc13db14	chore: highlight effect in tree (#17835) ... Another QoL improvement to `log_effect_tree` — if you pass an array of effects as the second argument, it will highlight them in the tree. It will also italicise any effects that currently have the `INERT` flag.	1 week ago
Rich Harris	86ec210866	fix: correctly add `__svelte_meta` after else-if chains (#17830) ... While looking into something else I spotted the fact that we use `false` to indicate 'else' in an `{#if ...}` block (whether there's an `else` block to render or not). If we instead use `-1`, and use `<!--[0-->` to indicate that the first block in an if-elseif chain was rendered... - instead of `<!--[-->`, we do `<!--[0-->` - instead of `<!--[!-->`, we do `<!--[-1-->` - all others stay the same ...we can simplify things a bit — the `key` argument to `update_branch` is always a number (which probably has some microscopic benefits in terms of making it monomorphic when `else` is defined, and less polymorphic when it isn't), and the hydration mismatch code only needs to consider one type of hydration marker. In the process, I discovered a bug — the dev-time `add_locations` function fails on hydration markers like `<!--[1-->`. This PR fixes it.	1 week ago
Rich Harris	7717ba01b4	fix: preserve each items that are needed by pending batches (#17819) ... This fixes a longstanding TODO with each blocks: currently, if any effects aren't used in the current batch at the moment of reconciliation, they are destroyed. Subsequent batches therefore end up recreating them. This is wasteful at the best of times, but if the effect contains any async work, that work has to be restarted. This PR fixes it by preserving any effects that correspond to the keys of pending batches. It _does_ mean that we need to iterate over each `keys` map for each pending batch in which an each block re-ran, but that is a rare scenario. This feels preferable to the alternative approaches.	1 week ago
Mathias Picker	791d5e332c	perf: cache element interactivity and source line splitting (#17839) ... ## Summary Two small compiler optimizations that reduce redundant work: - **Cache `element_interactivity` per element in a11y checks**: `check_element` was calling `element_interactivity()` up to 10 times per element (via `is_interactive_element`, `is_non_interactive_element`, `is_static_element` wrappers), each time re-iterating schema arrays. Now computed once after building the attribute map and reused. The now-unused wrapper functions are removed. - **Split source lines once in `state.set_source`**: Every compiler warning called `get_code_frame` which split the entire source string with `source.split('\n')`. Now the split happens once in `set_source()` and is exported as `state.source_lines`, naturally cleared by `reset()`. ## Benchmark Synthetic component (80 state vars, 30 each blocks, ~1300 lines): ``` Min Best3 Median Before 66.55ms 67.03ms 73.44ms After 61.14ms 61.90ms 70.63ms Improvement 8.1% 7.7% 3.8% ``` Realistic component (~80 lines, ~25 elements, few warnings): **~1-4%** improvement. The a11y cache scales with element count, the source.split saving scales with warning count. ## Test plan - [x] All 326 validator tests pass (includes all a11y tests) - [x] All 5671 runtime tests pass - [x] 145 compiler-error tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	1 week ago
Rich Harris	4aa3777271	chore: better log_effect_tree (#17833) ... While working on the reactivity it's very helpful to be able to log a snapshot of the effect tree. This PR augments the existing `log_effect_tree` helper by marking unreachable-but-dirty effects, like so: <img width="333" height="415" alt="image" src="https://github.com/user-attachments/assets/2c7501f7-b845-4271-b534-3a8be0ff62ee" /> (I had thought `log_inconsistent_branches` was designed to help with this but it didn't work for me. Do we need both? cc @dummdidumm) --------- Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>	1 week ago
Rich Harris	15e1e73f9c	chore: add `batch.id` property (#17831) ... I cannot tell you how many times I have temporarily added this code to make it easier to debug some async stuff. I am extremely bored of doing so. I'm just going to add it to `main` to save myself the annoyance. We can remove it once everything async is stable	1 week ago
github-actions[bot]	d4c78292ed	Version Packages (#17812) ... 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@5.53.6 ### Patch Changes - perf: optimize parser hot paths for faster compilation ([#17811](https://github.com/sveltejs/svelte/pull/17811)) - fix: `SvelteMap` incorrectly handles keys with `undefined` values ([#17826](https://github.com/sveltejs/svelte/pull/17826)) - fix: SvelteURL `search` setter now returns the normalized value, matching native URL behavior ([#17828](https://github.com/sveltejs/svelte/pull/17828)) - fix: visit synthetic value node during ssr ([#17824](https://github.com/sveltejs/svelte/pull/17824)) - fix: always case insensitive event handlers during ssr ([#17822](https://github.com/sveltejs/svelte/pull/17822)) - chore: more efficient effect scheduling ([#17808](https://github.com/sveltejs/svelte/pull/17808)) - perf: optimize compiler analysis phase ([#17823](https://github.com/sveltejs/svelte/pull/17823)) - fix: skip redundant batch.apply ([#17816](https://github.com/sveltejs/svelte/pull/17816)) - chore: null out current_batch before committing branches ([#17809](https://github.com/sveltejs/svelte/pull/17809)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2 weeks ago
Mathias Picker	361b32c7cd	fix: SvelteURL search setter uses unnormalized value (#17828) ... ## Summary - The `SvelteURL` `search` setter stored the raw input `value` instead of `super.search`, unlike every other setter in the class - This caused `url.search` to return incorrect values when the URL API normalizes the input (e.g. adding the `?` prefix, or stripping a lone `?`) - For example: `url.search = 'foo=bar'` would return `'foo=bar'` instead of `'?foo=bar'` ## Test plan - [x] Added `url.search normalizes value` test covering: - Setting search without `?` prefix - Setting search with `?` prefix (existing behavior) - Setting search to lone `?` (normalized to `""`) - [x] All existing reactivity tests pass (46/46) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Rich Harris	6e9b2a6fd8	docs: best practices (#17804) ... Based on #17727 but with a few changes: - smaller (fewer tokens) - removed some bits that are really just summarising existing docs - added an explicit 'don't use these legacy features' section - shuffled some things around a bit --------- Co-authored-by: paoloricciuti <ricciutipaolo@gmail.com> Co-authored-by: Federico Varano <50919335+fvarano@users.noreply.github.com> Co-authored-by: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>	2 weeks ago
Mathias Picker	1043f79d1e	perf: optimize compiler analysis phase (#17823) ... ## Summary Two optimizations to the compiler's analysis phase: - **Cache `ignore_stack` snapshots instead of `structuredClone` on every node.** The universal `_` visitor in the analysis walk runs on every AST node and calls `structuredClone(ignore_stack)` each time. In practice, `svelte-ignore` comments are rare (0–5 per component), so 99%+ of nodes deep-clone an unchanged stack. This adds a copy-on-write cache that only re-creates the snapshot when `push_ignore`/`pop_ignore` actually change the stack. - **Walk the CSS stylesheet once instead of once per element.** `prune()` was called in a loop for each element, each time doing a full `walk()` of the stylesheet AST. This restructures the loop so the stylesheet is walked once, and the element iteration happens inside the `ComplexSelector` visitor. ## Benchmarks Compiled each component 500 times (after 50 warmup iterations), measuring average time per `compile()` call: | Component | Before | After | Speedup | |---|---|---|---| | `has` (80+ CSS selectors, 12 elements) | 3.405 ms | 2.680 ms | **21% faster** | | `siblings-combinator-each-nested` (65 CSS rules, 15 elements) | 2.034 ms | 1.575 ms | **23% faster** | | synthetic (100 CSS rules, 50 elements) | 10.099 ms | 4.564 ms | **55% faster** | The CSS pruning optimization scales with `elements × CSS rules` — the more elements a component has, the bigger the win since we go from N stylesheet walks down to 1. The `structuredClone` fix helps every component regardless of CSS, eliminating ~500–2000 deep clones per compile (one per AST node) and replacing them with 0–5 (one per `svelte-ignore` comment). For typical real-world components with 10–20 elements and some CSS, expect roughly **20–30% faster compilation** in the analysis phase. ## Test plan - [x] Full test suite passes (7329 tests, 0 failures) - [x] CSS pruning tests pass (selector matching, scoping, unused rule detection) - [x] `svelte-ignore` behavior unchanged (snapshot is consumed read-only via `.has()`/`.some()`) 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Paolo Ricciuti	b6faa2a905	fix: always case insensitive event handlers during ssr (#17822) ... Fixes events not being stripped on svg, mathml and custom elements. ### Before submitting the PR, please make sure you do the following - [x] 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: Simon H <5968653+dummdidumm@users.noreply.github.com>	2 weeks ago
Paolo Ricciuti	e3d277b000	fix: visit synthetic value node during ssr (#17824) ... Closes #17821 ### Before submitting the PR, please make sure you do the following - [x] 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`	2 weeks ago
Tee Ming	a10cf95ca7	chore: add funding manifest URL (#17827) ... Related to https://github.com/sveltejs/svelte.dev/pull/1632 This will allow us to apply for a grant from floss.fund ### 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 - [ ] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [ ] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [ ] Run the tests with `pnpm test` and lint the project with `pnpm lint`	2 weeks ago
Mathias Picker	18db0cab86	fix: SvelteMap incorrectly handles keys with `undefined` values (#17826) ... ## Summary `SvelteMap` had two bugs related to how it checked for key existence internally: ### 1. `has()` and `get()` returned wrong results for keys with `undefined` values Both methods used `super.get(key) !== undefined` to determine if a key existed before creating a per-key reactive source. This fails for keys whose value is legitimately `undefined`, causing: - `has(key)` to return `false` for existing keys with `undefined` values - `get(key)` to skip creating a per-key source and fall back to tracking `version`, resulting in over-notification **Fix:** Replace `super.get(key) !== undefined` with `super.has(key)` in both `has()` and `get()`, matching the pattern already used in `SvelteSet`. ### 2. `delete()` skipped reactive updates when a key had no per-key source The `size` and `version` reactive updates were inside the `if (s !== undefined)` block, meaning they only fired when a per-key source existed (i.e., someone had previously called `has()` or `get()` on that specific key). If a key was added via the constructor or `set()` but never individually read, deleting it would not trigger reactive updates for effects depending on `size` or iterators. **Fix:** Move `set(this.#size, super.size)` and `increment(this.#version)` to a separate `if (res)` block so they fire whenever a key is actually deleted, regardless of whether a per-key source existed. ### Before fix ```js const map = new SvelteMap([['foo', undefined]]); map.has('foo'); // false (should be true) map.get('foo'); // undefined but tracks version instead of per-key source ``` ### After fix ```js const map = new SvelteMap([['foo', undefined]]); map.has('foo'); // true map.get('foo'); // undefined with correct per-key tracking ``` ## Test plan Tests are in `packages/svelte/src/reactivity/map.test.ts`: - `map.has()` returns `true` for constructor-initialized keys with `undefined` values - `map.get()` returns `undefined` with proper per-key reactive tracking - `map.delete()` triggers `has()`/`get()` reactivity for undefined-valued keys - `map.set(key, undefined)` followed by `has()`/`get()` works correctly - `map.delete()` triggers `size` reactivity for keys that were never individually read (no per-key source) - All existing tests pass unchanged 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Rich Harris	3fc4bc6774	chore: remove unused is_flushing variable (#17820) ... as of a few PRs ago this variable is unused	2 weeks ago
Rich Harris	16a13517ef	fix: skip redundant batch.apply (#17816) ... tiny fix — just realised we're calling `this.apply()` (via `this.activate()`) unnecessarily, since it will happen again immediately after in `flush_effects`	2 weeks ago
Gautier Ben Aïm	10380c2309	docs: fix list item (#17815) ... Fixes the formatting for this list https://svelte-dev-git-sync-svelte-svelte.vercel.app/docs/svelte/v5-migration-guide#Whitespace-handling-changed Follow up #17806	2 weeks ago
Rich Harris	04ba134d33	docs: flesh out `attribute_invalid_sequence_expression` message (#17789) ... closes #1404	2 weeks ago
Gautier Ben Aïm	d83e4be1f0	docs: document the {' '} trick (#17806) ... Hi! I run into this issue today, and found the fix in https://github.com/sveltejs/svelte/issues/16680#issuecomment-3229435832 I thought it would be a nice addition to the documentation (it's where I looked first) ### 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:`. - [ ] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [ ] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Rich Harris <hello@rich-harris.dev>	2 weeks ago
dependabot[bot]	fc67c9cfe9	chore(deps-dev): bump rollup from 4.52.5 to 4.59.0 (#17810) ... Bumps [rollup](https://github.com/rollup/rollup) from 4.52.5 to 4.59.0. <details> <summary>Release notes</summary> <p><em>Sourced from <a href="https://github.com/rollup/rollup/releases">rollup's releases</a>.</em></p> <blockquote> <h2>v4.59.0</h2> <h2>4.59.0</h2> <p><em>2026-02-22</em></p> <h3>Features</h3> <ul> <li>Throw when the generated bundle contains paths that would leave the output directory (<a href="https://redirect.github.com/rollup/rollup/issues/6276">#6276</a>)</li> </ul> <h3>Pull Requests</h3> <ul> <li><a href="https://redirect.github.com/rollup/rollup/pull/6275">#6275</a>: Validate bundle stays within output dir (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> </ul> <h2>v4.58.0</h2> <h2>4.58.0</h2> <p><em>2026-02-20</em></p> <h3>Features</h3> <ul> <li>Also support <code>__NO_SIDE_EFFECTS__</code> annotation before variable declarations declaring function expressions (<a href="https://redirect.github.com/rollup/rollup/issues/6272">#6272</a>)</li> </ul> <h3>Pull Requests</h3> <ul> <li><a href="https://redirect.github.com/rollup/rollup/pull/6256">#6256</a>: docs: document PreRenderedChunk properties including isDynamicEntry and isImplicitEntry (<a href="https://github.com/njg7194"><code>@​njg7194</code></a>, <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6259">#6259</a>: docs: Correct typo and improve sentence structure in docs for <code>output.experimentalMinChunkSize</code> (<a href="https://github.com/millerick"><code>@​millerick</code></a>, <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6260">#6260</a>: fix(deps): update rust crate swc_compiler_base to v47 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6261">#6261</a>: fix(deps): lock file maintenance minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6262">#6262</a>: Avoid unnecessary cloning of the code string (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6263">#6263</a>: fix(deps): update minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6265">#6265</a>: chore(deps): lock file maintenance (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6267">#6267</a>: fix(deps): update minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6268">#6268</a>: chore(deps): update dependency eslint-plugin-unicorn to v63 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6269">#6269</a>: chore(deps): update dependency lru-cache to v11 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6270">#6270</a>: chore(deps): lock file maintenance (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6272">#6272</a>: forward NO_SIDE_EFFECTS annotations to function expressions in variable declarations (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> </ul> <h2>v4.57.1</h2> <h2>4.57.1</h2> <p><em>2026-01-30</em></p> <h3>Bug Fixes</h3> <ul> <li>Fix heap corruption issue in Windows (<a href="https://redirect.github.com/rollup/rollup/issues/6251">#6251</a>)</li> <li>Ensure exports of a dynamic import are fully included when called from a try...catch (<a href="https://redirect.github.com/rollup/rollup/issues/6254">#6254</a>)</li> </ul> <h3>Pull Requests</h3> <ul> <li><a href="https://redirect.github.com/rollup/rollup/pull/6251">#6251</a>: fix: Isolate and cache <code>process.report.getReport()</code> calls in a child process for robust environment detection (<a href="https://github.com/alan-agius4"><code>@​alan-agius4</code></a>, <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> </ul> <!-- raw HTML omitted --> </blockquote> <p>... (truncated)</p> </details> <details> <summary>Changelog</summary> <p><em>Sourced from <a href="https://github.com/rollup/rollup/blob/master/CHANGELOG.md">rollup's changelog</a>.</em></p> <blockquote> <h2>4.59.0</h2> <p><em>2026-02-22</em></p> <h3>Features</h3> <ul> <li>Throw when the generated bundle contains paths that would leave the output directory (<a href="https://redirect.github.com/rollup/rollup/issues/6276">#6276</a>)</li> </ul> <h3>Pull Requests</h3> <ul> <li><a href="https://redirect.github.com/rollup/rollup/pull/6275">#6275</a>: Validate bundle stays within output dir (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> </ul> <h2>4.58.0</h2> <p><em>2026-02-20</em></p> <h3>Features</h3> <ul> <li>Also support <code>__NO_SIDE_EFFECTS__</code> annotation before variable declarations declaring function expressions (<a href="https://redirect.github.com/rollup/rollup/issues/6272">#6272</a>)</li> </ul> <h3>Pull Requests</h3> <ul> <li><a href="https://redirect.github.com/rollup/rollup/pull/6256">#6256</a>: docs: document PreRenderedChunk properties including isDynamicEntry and isImplicitEntry (<a href="https://github.com/njg7194"><code>@​njg7194</code></a>, <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6259">#6259</a>: docs: Correct typo and improve sentence structure in docs for <code>output.experimentalMinChunkSize</code> (<a href="https://github.com/millerick"><code>@​millerick</code></a>, <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6260">#6260</a>: fix(deps): update rust crate swc_compiler_base to v47 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6261">#6261</a>: fix(deps): lock file maintenance minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6262">#6262</a>: Avoid unnecessary cloning of the code string (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6263">#6263</a>: fix(deps): update minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6265">#6265</a>: chore(deps): lock file maintenance (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6267">#6267</a>: fix(deps): update minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6268">#6268</a>: chore(deps): update dependency eslint-plugin-unicorn to v63 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6269">#6269</a>: chore(deps): update dependency lru-cache to v11 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6270">#6270</a>: chore(deps): lock file maintenance (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6272">#6272</a>: forward NO_SIDE_EFFECTS annotations to function expressions in variable declarations (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> </ul> <h2>4.57.1</h2> <p><em>2026-01-30</em></p> <h3>Bug Fixes</h3> <ul> <li>Fix heap corruption issue in Windows (<a href="https://redirect.github.com/rollup/rollup/issues/6251">#6251</a>)</li> <li>Ensure exports of a dynamic import are fully included when called from a try...catch (<a href="https://redirect.github.com/rollup/rollup/issues/6254">#6254</a>)</li> </ul> <h3>Pull Requests</h3> <ul> <li><a href="https://redirect.github.com/rollup/rollup/pull/6251">#6251</a>: fix: Isolate and cache <code>process.report.getReport()</code> calls in a child process for robust environment detection (<a href="https://github.com/alan-agius4"><code>@​alan-agius4</code></a>, <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6252">#6252</a>: chore(deps): update dependency lru-cache to v11 (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot])</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6253">#6253</a>: chore(deps): lock file maintenance minor/patch updates (<a href="https://github.com/renovate"><code>@​renovate</code></a>[bot], <a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> <li><a href="https://redirect.github.com/rollup/rollup/pull/6254">#6254</a>: Fully include dynamic imports in a try-catch (<a href="https://github.com/lukastaegert"><code>@​lukastaegert</code></a>)</li> </ul> <!-- raw HTML omitted --> </blockquote> <p>... (truncated)</p> </details> <details> <summary>Commits</summary> <ul> <li><a href="ae846957f1"><code>ae84695</code></a> 4.59.0</li> <li><a href="b39616e917"><code>b39616e</code></a> Update audit-resolve</li> <li><a href="c60770d7aa"><code>c60770d</code></a> Validate bundle stays within output dir (<a href="https://redirect.github.com/rollup/rollup/issues/6275">#6275</a>)</li> <li><a href="33f39c1f20"><code>33f39c1</code></a> 4.58.0</li> <li><a href="b61c40803b"><code>b61c408</code></a> forward NO_SIDE_EFFECTS annotations to function expressions in variable decla...</li> <li><a href="7f00689ec9"><code>7f00689</code></a> Extend agent instructions</li> <li><a href="e7b2b85af0"><code>e7b2b85</code></a> chore(deps): lock file maintenance (<a href="https://redirect.github.com/rollup/rollup/issues/6270">#6270</a>)</li> <li><a href="2aa5da9baf"><code>2aa5da9</code></a> fix(deps): update minor/patch updates (<a href="https://redirect.github.com/rollup/rollup/issues/6267">#6267</a>)</li> <li><a href="4319837c54"><code>4319837</code></a> chore(deps): update dependency lru-cache to v11 (<a href="https://redirect.github.com/rollup/rollup/issues/6269">#6269</a>)</li> <li><a href="c3b6b4bdc4"><code>c3b6b4b</code></a> chore(deps): update dependency eslint-plugin-unicorn to v63 (<a href="https://redirect.github.com/rollup/rollup/issues/6268">#6268</a>)</li> <li>Additional commits viewable in <a href="https://github.com/rollup/rollup/compare/v4.52.5...v4.59.0">compare view</a></li> </ul> </details> <details> <summary>Install script changes</summary> <p>This version modifies <code>prepare</code> script that runs during installation. Review the package contents before updating.</p> </details> <br /> [](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- <details> <summary>Dependabot commands and options</summary> <br /> You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself) You can disable automated security fix PRs for this repo from the [Security Alerts page](https://github.com/sveltejs/svelte/network/alerts). </details> Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2 weeks ago
Mathias Picker	efb651cd33	perf: optimize parser hot paths for ~18% faster compilation (#17811) ... ## Summary Optimizes the Svelte compiler's parser phase — the hot path that runs on every file compilation during development (HMR). The changes are surgical micro-optimizations to 7 files in `packages/svelte/src/compiler/phases/1-parse/`, with no architectural changes. ### Changes - **`Parser.match()` — `slice` → `startsWith`**: Avoids creating a new substring on every multi-char match call (called thousands of times per compilation) - **`Parser.match_regex()` — `slice` → sticky flag**: Uses `lastIndex` + `y` flag instead of slicing the entire template string on every regex match. All 14 regex patterns passed to `match_regex`/`read` across 4 files updated with `y` flag. - **`Parser.allow_whitespace()` / `require_whitespace()` — regex → charCode**: Replaces `regex_whitespace.test()` with numeric charCode comparisons in a tight loop (called hundreds of times per compilation). Covers the full `\s` character set with a fast path for common ASCII whitespace. - **Text parser — string concatenation → `slice`**: Replaced `data += template[index++]` loop (O(n²)) with tracking start position + single `slice()` call (O(n)) - **`read_sequence` — string concatenation → `slice`**: Same pattern — derive `raw` from `template.slice()` in `flush()` instead of char-by-char concatenation - **`is_valid_element_name()` — inline regexes → module-level constants**: Extracted 2 regex literals to module scope - **Dynamic `new RegExp()` → `indexOf`**: Replaced `parser.read_until(new RegExp(...))` with `template.indexOf()` for script/style closing tags - **`match_bracket` — `Array.includes` → `Set.has`**: Pre-computes close bracket values as a `Set` for O(1) lookups ## Benchmark A benchmark script was written that: 1. Compiles 5 real test components of varying complexity (a11y validators, form bindings, component migration output, rich selects) 2. Compiles 2 synthetic stress-test templates (500 elements and 2000 elements with expressions and entities) 3. Runs 50 warmup iterations for parse, 20 for compile (JIT warmup) 4. Forces GC between benchmarks via `--expose-gc` 5. Measures both parse-only and full compilation (parse + analyze + transform + codegen) ### Parse-only results | Component | Before | After | Speedup | |---|---|---|---| | a11y-role-supports-aria-props (371 lines) | 2.410ms | 2.129ms | **-11.7%** | | form-default-value-spread (199 lines) | 1.726ms | 1.360ms | **-21.2%** | | svelte-component (251 lines) | 1.925ms | 1.648ms | **-14.4%** | | select-with-rich-content (157 lines) | 0.795ms | 0.636ms | **-20.0%** | | rich-select (173 lines) | 0.807ms | 0.637ms | **-21.1%** | | synthetic-large (500 elements) | 2.560ms | 1.547ms | **-39.6%** | | synthetic-huge (2000 elements) | 136.849ms | 114.115ms | **-16.6%** | | **Total** | **147.071ms** | **122.072ms** | **-17.0%** | ### Full compile results | Component | Before | After | Speedup | |---|---|---|---| | a11y-role-supports-aria-props | 25.407ms | 21.990ms | **-13.4%** | | form-default-value-spread | 10.711ms | 9.422ms | **-12.0%** | | svelte-component | 10.304ms | 8.481ms | **-17.7%** | | select-with-rich-content | 5.986ms | 4.694ms | **-21.6%** | | rich-select | 6.010ms | 5.059ms | **-15.8%** | | synthetic-large (500 elements) | 30.511ms | 25.196ms | **-17.4%** | | synthetic-huge (2000 elements) | 932.801ms | 764.794ms | **-18.0%** | | **Total** | **1021.729ms** | **839.637ms** | **-17.8%** | Benchmarked on macOS, Node.js, Apple Silicon. The parse improvements carry through to end-to-end compile time since the parser is a significant portion of the compilation pipeline. Text-heavy templates benefit the most (up to 40% faster parse). Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Rich Harris	dd5b587bd3	chore: simplify batch.flush (#17814) ... another extraction from #17805. I always felt bad about `this.process([])`, and this PR replaces it with the steps that actually occur — even though this is arguably duplicative, I find it much easier to understand. It also allows us to avoid activating batches with no queued effects, thanks to the change in #17809. This saves us a bit of work in a not-that-uncommon case. ### Before submitting the PR, please make sure you do the following - [x] 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. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] 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`	2 weeks ago
Rich Harris	5e28508377	chore: simplify create effect (#17813) ... follow-up to #17808. This makes it a bit more explicit _why_ we do certain things in `create_effect`, and gets rid of a redundant parameter ### Before submitting the PR, please make sure you do the following - [x] 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. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] 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`	2 weeks ago
Rich Harris	5bd4699539	chore: more efficient effect scheduling (#17808) ... This extracts part of #17805 into its own PR that can be merged independently. Today, if a (non-render) effect is created during traversal (e.g. an `{#if condition}` block becomes true, and an `$effect` is created somewhere inside it) then it goes through `schedule_effect`, ultimately causing the loop in `flush_effects` to run again. This is wasteful. We can instead push to an array — `collected_effects` — which is flushed following the first traversal. By using `collected_effects !== null` as a proxy for 'is traversing', we can also simplify the bail-out logic inside `schedule_effect` and make it work in more cases. Bailing out means that in the case that a signal is written to during traversal (which is the case for `each` blocks, for example), we can avoid triggering another turn of the loop because we know that the affected effects are about to be discovered as a result of the ongoing traversal. All this brings us slightly closer to the intermediate goal in #17805 of ensuring that scheduled effects always belong to a specific batch. No test for this because it shouldn't have any user-observable impact, though I've added a changeset out of an abundance of caution.	2 weeks ago
Rich Harris	b76cd5cafc	chore: null out current_batch before committing branches (#17809) ... Another small tweak extracted from #17805, just to make that diff a bit more legible. By passing the `batch` to the branch commit callback, we don't need to rely on the value of `current_batch` being the same as the batch currently being processed. That gives us more control over the order of operations — for example we can null out `current_batch` _before_ committing branches, which is important (at present, if a state change occurs while those branches are being committed, it will belong to the current batch, but the resulting effects will happen in the context of a _new_ batch, which is something we need to avoid for the sake of #17805). ### Before submitting the PR, please make sure you do the following - [x] 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. - [ ] 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`	2 weeks ago
Elliott Johnson	fa4f1c45f4	chore: run `prettier` (#17803) ... Just fixing CI 🙄	2 weeks ago
github-actions[bot]	ed14b499d6	Version Packages (#17802) ... 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@5.53.5 ### Patch Changes - fix: escape `innerText` and `textContent` bindings of `contenteditable` ([`0df5abcae223058ceb95491470372065fb87951d`](0df5abcae2)) - fix: sanitize `transformError` values prior to embedding in HTML comments ([`0298e979371bb583855c9810db79a70a551d22b9`](0298e97937)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2 weeks ago
Paolo Ricciuti	0df5abcae2	Merge commit from fork ... * fix: escape `innerText` and `textContent` bindings of `contenteditable` * fix: better if else structure	2 weeks ago
Elliott Johnson	0298e97937	Merge commit from fork ... * fix: sanitize `transformError` values prior to embedding in HTML comments * did a little dumb	2 weeks ago
github-actions[bot]	96fd3ce763	Version Packages (#17786) ... 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@5.53.4 ### Patch Changes - fix: set server context after async transformError ([#17799](https://github.com/sveltejs/svelte/pull/17799)) - fix: hydrate if blocks correctly ([#17784](https://github.com/sveltejs/svelte/pull/17784)) - fix: handle default parameters scope leaks ([#17788](https://github.com/sveltejs/svelte/pull/17788)) - fix: prevent flushed effects from running again ([#17787](https://github.com/sveltejs/svelte/pull/17787)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2 weeks ago
Simon H	1b3e660519	fix: prevent flushed effects from running again (#17787) ... We never cleared the list of (maybe)dirty_effects on the assumption that once a batch has run them it's complete. But that's not the case when a boundary has a pending snippet, in which case the pending snippet shows up, so `blocking_pending` is already 0 and effects are flushed. That can lead to effects being run unnecessarily, even leading to infinite loops. So we clear them. This is safe because any additional effects would either be scheduled by the boundary (which keeps track of the offscreen effects created while the pending snippet is shown, and schedules them once the pending snippet goes away) or by unskipping skipped branches (which reschedules the effects inside it) Fixes #17717 After creating the test I noticed it fails when run together with other tests, but not alone, which lead me to discover that we're missing an `unset_context`. I also added clearing of `#skipped_branches` just to be safe.	2 weeks ago
Elliott Johnson	f6e8b1d11e	chore: require pr number as input when manually invoking pkg.pr.new (#17797)	2 weeks ago
Simon H	673a1ab964	fix: set server context after async transformError (#17799) ... This will get the tests in https://github.com/sveltejs/kit/pull/15308 green, right now they fail because page state cannot be found because context not available	2 weeks ago
Maurício Kishi	3a289797bd	fix: handle default parameters scope leaks (#17788) ... Use separate scopes for function declarations/expressions and function bodies. This prevents variable declarations from leaking into default parameter initialization expressions. Closes #17785. ### Before submitting the PR, please make sure you do the following - [x] 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`	2 weeks ago
Elliott Johnson	fef7e0f742	chore: remove ecosystem-ci-gate workflow (#17795) ... The app shared between Kit and Svelte takes care of this now ### 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 - [ ] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [ ] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [ ] Run the tests with `pnpm test` and lint the project with `pnpm lint`	2 weeks ago
Simon H	fcdc0289db	fix: hydrate if blocks correctly (#17784) ... We were not using the correct node to analyze the if block marker Fixes #17751	2 weeks ago