Fixes#17720
## Problem
The `{@const}` tag was being printed with a trailing semicolon,
producing invalid Svelte syntax like:
{@const a = 1;}
This happened because the `ConstTag` visitor in the printer was
delegating to esrap's `VariableDeclaration` handler, which always
appends a semicolon (correct for JS, but wrong for Svelte template
syntax).
## Solution
Instead of delegating to `VariableDeclaration`, the `ConstTag` visitor
now manually prints the tag by:
- Writing `{@const ` directly
- Iterating through declarators and visiting each one
- Separating multiple declarations with commas
- Closing with `}` — no trailing semicolon
## Before
{@const a = 1;}
{@const a = 1, b = 2;}
## After
{@const a = 1}
{@const a = 1, b = 2}
## Changes
- `packages/svelte/src/compiler/print/index.js` — fixed `ConstTag`
visitor
- `packages/svelte/tests/print/samples/const-tag/output.svelte` —
updated expected test output
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Rich Harris <hello@rich-harris.dev>
Co-authored-by: Rich Harris <rich.harris@vercel.com>
## Fix: #17881
### Root Cause
When a dynamic component switches (e.g. `<Component />`), branch effects
are destroyed via `destroy_effect()`.
However, the `effect.b` (Boundary reference) field was not cleared
alongside other references (`next`, `prev`, `ctx`, `deps`, `fn`,
`nodes`, `ac`).
As a result, destroyed effects retained a reference to the `Boundary`
instance, which holds references to component state and child effects.
This prevented destroyed component subtrees from being garbage
collected, causing memory usage to grow during repeated component
switching.
### Solution
Clear the boundary reference during effect destruction.
```diff
effect.next =
effect.prev =
effect.teardown =
effect.ctx =
effect.deps =
effect.fn =
effect.nodes =
effect.ac =
+ effect.b =
null;
```
### Test Plan
* All existing tests pass:
* runtime-runes: 2,459
* runtime-legacy: 3,294
* signals: 96
* Total: 5,849 tests
* Added a dynamic component switching test that toggles components
repeatedly and verifies correct DOM output.
### Validation
Reproduced the issue using the example from #17881.
After applying the fix:
* Memory usage stabilizes during repeated component switching
* Destroyed components are properly reclaimed by the garbage collector
* No behavioral regressions observed
### Impact
* Fixes memory leak in dynamic component switching
* Minimal, safe change
* No API or behavior changes
---------
Co-authored-by: Rich Harris <rich.harris@vercel.com>
We were just putting each statement into its own promise. Besides this
being bad for perf, it also introduces subtle timing issues - the
execution order of the code could change in bad ways. Fixes#17940
Closes#17972
Claude found this fix I had a look and I think it makes sense (we are
injecting a new comment which messes up the marching during hydration).
I'm slightly confused why this only applied to `css_props` but I guess
that's because there's an "hidden" element there which makes it special.
I don't super-like the `if` situation, but I guess it is what it is.
Also the test was using `hmr` without `dev` and this brought to my
attention that we were just assuming components return something while
it's not the case...I guess it doesn't really matter unless you are
using `hmr` in prod which is not a thing but fixing this is simple so we
might just as well doing it
This fixes an awkward bug with `each` blocks containing `await`,
especially keyed `each` blocks.
If you do `array.push(...)` multiple times in distinct batches,
something weird happens — to the `each` block, the array looks this...
```js
[1]
```
...then this...
```js
[undefined, 2]
```
...then this...
```js
[undefined, undefined, 3]
```
...and so on. That's because as far as Svelte's reactivity is concerned,
what we're _really_ doing is assigning to `array[0]` then `array[1]`
then `array[2]`. Those (along with `array.length`) are each backed by
independent sources, which we can rewind individually when we need to
'apply' a batch. When it comes to sources that actually _are_
independent, this is useful, since we apply the changes from batch B to
the DOM while we're still waiting for a promise in batch A to resolve.
But in this case it's not ideal, because you would expect these changes
to accumulate.
In particular, this fails with keyed `each` blocks because duplicate
keys are disallowed (assuming the key function doesn't break on
`undefined` _before_ the duplicate check happens).
This PR fixes it by stacking batches that are interconnected.
Specifically, if a later batch has some (but not all) sources in common
with an earlier batch, then when we apply the batch we include the
sources from the earlier batch, and block it until the earlier batch
commits. When the earlier batch commits, it will check to see if doing
so unblocks any later batches, and if so process them.
In the course of working on this I realised that `SvelteSet` and
`SvelteMap` aren't async-ready — will follow up this PR with ones for
those.
Fixes#17050
---------
Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
Co-authored-by: Simon Holthausen <simon.holthausen@vercel.com>
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@5.54.0
### Minor Changes
- feat: allow `css`, `runes`, `customElement` compiler options to be
functions ([#17951](https://github.com/sveltejs/svelte/pull/17951))
### Patch Changes
- fix: reinstate reactivity loss tracking
([#17801](https://github.com/sveltejs/svelte/pull/17801))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Alternative to #17950. Closes#17952
The goal of this is to allow svelte.config.js to contain functions for
setting certain options, so that there's a single source of truth for
everything that needs to interact with Svelte config (plugins, editor
extensions, etc):
```js
// svelte.config.js
export default {
compilerOptions: {
css: ({ filename }) => filename.endsWith('/OG.svelte') ? 'injected' : 'external',
experimental: {
async: true
},
runes: ({ filename }) => !filename.split(/\/\\/).includes('node_modules')
}
};
```
Once this ships, we can deprecate `dynamicCompileOptions` in
`vite-plugin-svelte`.
### 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`
We commented out this code in #17038 because it was broken. I suspect it
was broken because we weren't correctly calling `unset_context` inside
`run`, leading to false positives — this is now fixed, and as such I
_think_ we can safely reinstate it.
One small change — I got rid of the `was_read` check. I assume this
existed to prevent duplicate warnings, but it actually causes false
negatives in the case where you read a signal while the reaction is
being tracked then again while it's untracked.
### 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: Tee Ming <chewteeming01@gmail.com>
The offscreen branch was missing the "resume inert effects" logic that
was just below; it never reached that because of the early continue.
Fixes#17851
Fixes
https://github.com/sveltejs/svelte/issues/17918#issuecomment-4054067024.
The issue here was that in `boundary.#render`, if `this.#pending_count >
0` we yoink the content out of the DOM so we can replace it with the
`pending` fragment. This works by taking everything from
`effect.nodes.start` to `effect.nodes.end` and putting it in a
`DocumentFragment`.
With HMR, that doesn't work, because the effect with the nodes is buried
inside the HMR effect. This fixes it.
Draft because I'd like to try this out in a few more places before
merging.
Our "hey this is a thunk invoking a function, let's flatten that" logic
caused a bug where lazily-initialized functions where eagerly referenced
in the template effect. That causes a nullpointer.
Ensuring these variables are always referenced in a closure fixes#17404
---------
Co-authored-by: Rich Harris <rich.harris@vercel.com>
Batches that are made stale (because of a `STALE_REACTION`) can end up
sticking around indefinitely, forcing every subsequent batch into
time-traveling mode and causing incorrect `previous` values to be
rendered.
This partially fixes it, by discarding any older batches that are
subsets of a batch currently being committed. It's not a complete fix,
though — if an earlier batch is stale but is _not_ a subset of the
committed batch, it becomes a zombie, and its changes will never be
applied. Haven't quite figured out how to think about that yet.
### 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`
While we don't officially document it, `untrack` also allows to opt out
of the "unsafe mutation" validation, which is what we test here.
For anyone coming across this: USE WITH CAUTION. This can cause graph
inconsistencies leading to wrong values on initial render
Doing this because we're gonna make use of it ourselves for remote
functions, and this ensures we don't accidentally regress.
Before #17805, all batches drew from the same `queued_root_effects` and
did reset them to the empty array when starting a flush. After the
refactoring roots are scheduled per batch. This introduces a possible
race condition where the same root is scheduled multiple times. It was
possible because of the rebase logic in `#commit` not clearing the array
of roots, so if you somehow flush that same batch later, you will end up
traversing a clean root.
(it is possible a bug like this always existed with rebasing it was just
impossible hard to trigger it before because everyone drew from the same
root effects array)
The fix is a bit more complicated than just checking if new roots where
added, we gotta check if we actually created async work before
traversing.
Fixes#17918
---------
Co-authored-by: Rich Harris <rich.harris@vercel.com>
Fixes#17924. This also DRYs stuff a bit by making `operator` an
argument to the runtime helper function, which means we only need two
variants of it: regular and async. It also makes it so that `=`
assignments don't use the getter, because they don't need to be done
lazily.
I've added `skip_no_async` to the new test, but I'm not entirely clear
on why it was failing the TestNoAsync run to begin with.
### 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 Holthausen <simon.holthausen@vercel.com>
With this, we can add invariants to the codebase so we can identify
problems like 'this batch already has roots scheduled', which indicate a
bug somewhere, without a) needing tests for scenarios that are
inherently hard to anticipate, or b) cluttering people's prod bundles
## Summary
Fixes#17148
When a `<select>` is focused inside an async boundary, the
`bind_select_value` effect gets deferred by the batch system, leaving
`select.__value` stale. If options then change dynamically (e.g. via
`{#each}`), the `MutationObserver` in `init_select` uses the stale
`__value`, snapping the select to the wrong option.
- Update `__value` in the change handler so it's always current, even
when the effect is deferred
- Update `__value` in the effect's early-return path (defensive fix for
when the effect runs but skips the DOM update)
## Test plan
- Added `select-dynamic-options-while-focused` test that renders a
`<select>` with dynamic `{#each}` options inside an async boundary,
selects a non-initial option while focused, adds another option, and
verifies the select retains the user's choice
- Verified existing `async-binding-update-while-focused-3` test still
passes
- All 7151 tests pass (`pnpm test`)
---------
Co-authored-by: Tee Ming <chewteeming01@gmail.com>
Co-authored-by: Rich Harris <rich.harris@vercel.com>
Co-authored-by: Rich Harris <hello@rich-harris.dev>
capture derived updates aswell so they become part of current/previous
so that `batch_values` computation is correct when e.g. using
`$state.eager` with a derived. Fixes#17849
Bumps [devalue](https://github.com/sveltejs/devalue) from 5.6.3 to
5.6.4.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/sveltejs/devalue/releases">devalue's
releases</a>.</em></p>
<blockquote>
<h2>v5.6.4</h2>
<h3>Patch Changes</h3>
<ul>
<li>
<p>87c1f3c: fix: reject <code>__proto__</code> keys in malformed
<code>Object</code> wrapper payloads</p>
<p>This validates the <code>"Object"</code> parse path and
throws when the wrapped value has an own <code>__proto__</code> key.</p>
</li>
<li>
<p>40f1db1: fix: ensure sparse array indices are integers</p>
</li>
<li>
<p>87c1f3c: fix: disallow <code>__proto__</code> keys in null-prototype
object parsing</p>
<p>This disallows <code>__proto__</code> keys in the
<code>"null"</code> parse path so null-prototype object
hydration cannot carry that key through parse/unflatten.</p>
</li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/sveltejs/devalue/blob/main/CHANGELOG.md">devalue's
changelog</a>.</em></p>
<blockquote>
<h2>5.6.4</h2>
<h3>Patch Changes</h3>
<ul>
<li>
<p>87c1f3c: fix: reject <code>__proto__</code> keys in malformed
<code>Object</code> wrapper payloads</p>
<p>This validates the <code>"Object"</code> parse path and
throws when the wrapped value has an own <code>__proto__</code> key.</p>
</li>
<li>
<p>40f1db1: fix: ensure sparse array indices are integers</p>
</li>
<li>
<p>87c1f3c: fix: disallow <code>__proto__</code> keys in null-prototype
object parsing</p>
<p>This disallows <code>__proto__</code> keys in the
<code>"null"</code> parse path so null-prototype object
hydration cannot carry that key through parse/unflatten.</p>
</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="6cbb3f5125"><code>6cbb3f5</code></a>
Version Packages (<a
href="https://redirect.github.com/sveltejs/devalue/issues/133">#133</a>)</li>
<li><a
href="40f1db13af"><code>40f1db1</code></a>
Merge commit from fork</li>
<li><a
href="87c1f3ce37"><code>87c1f3c</code></a>
Merge commit from fork</li>
<li>See full diff in <a
href="https://github.com/sveltejs/devalue/compare/v5.6.3...v5.6.4">compare
view</a></li>
</ul>
</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>
Fixes#17907. When hydrating, we were resolving the boundary in the
hydration batch rather than the batch created inside the
`queue_micro_task` inside `#hydrate_pending_content`. This meant that
effects got scheduled inside a batch that was already resolved.
### 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`
https://github.com/sveltejs/svelte/pull/17680#issuecomment-3888440736.
Errors that occur during traversal (not inside a template effect etc)
can leave dirty effects inside the effect tree, but with clean parents.
This means that
a) subsequent changes to their dependencies won't schedule them to
re-run
b) subsequent batch flushes won't 'reach' them unless a sibling effect
happens to be made dirty
The easiest way to fix this is to just repair the tree if traversal
fails. If you had a truly ginormous tree this could conceivably take a
noticeable amount of time, but that's probably better than the app just
being broken.
Note that this doesn't apply to errors that occur inside an error
boundary, because in that case the offending subtree gets destroyed.
This is just for errors that bubble all the way to the root.
Closes#17680, closes#17679.
Closes#17899 by importing `untrack` from the actual file instead of the
`index-client.js`. Verified by packing the library and launching a build
with it.
Fixes#17904 by wrapping the RHS in a `() =>`.
### 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`
This is part of me trying to figure out #17162. It feels less confusing
to rebase other branches after the current batch has been processed,
rather than sort of doing it in the middle (which is an artifact of
historical constraints that no longer apply).
No test because it doesn't change any user-observable behaviour (but I
added a changeset just in 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.
- [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`
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@5.53.10
### Patch Changes
- fix: re-process batch if new root effects were scheduled
([#17895](https://github.com/sveltejs/svelte/pull/17895))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
In some cases a new branch might create effects which via
reading/writing reschedule an effect, causing `this.#roots` to become
populated again. In this case we need to re-process the batch. Most of
the time this will just result in a cleanup of the dirtied branches
since other work is already handled via running the effects etc. - it's
still crucial, else the reactive graph becomes frozen since no new root
effects are scheduled.
Fixes#17891
---------
Co-authored-by: Rich Harris <rich.harris@vercel.com>
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@5.53.9
### Patch Changes
- fix: better `bind:this` cleanup timing
([#17885](https://github.com/sveltejs/svelte/pull/17885))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
This removes the `queue_micro_task`-workaround we employed in
`bind:this` in favor of a search for the nearest component effect /
effect that is still getting destroyed, whichever comes first.
We used `queue_micro_task` mainly due to timing issues with components
wanting to access the bound property on teardown still, and when nulling
it out on cleanup of the bind-this-effect itself, that was too early.
The microtask is too late though in some cases, when accessing
properties of objects that are no longer there. The targeted
upwards-walk solves this while keeping the binding around as long as
needed.
For that I had to add a new `DESTROYING` flag. We _could_ have done it
without one and by deleting code in `props.js` where we don't do
`get(d)` when the prop derived is destroyed, but I wanted to keep that
because you could still run into an access error if you e.g. access the
property in a timeout.
Alternative to #17862
In #17837 we added logic to not schedule another batch during
resumption. The logic in there turns out to be flawed - it's dangerous
to keep accessing inert block effects, because if they're nested they
could access properties that no longer exist (because the outer if makes
the inner if obsolete).
So this PR basically reverts #17837 and instead schedules another batch
again under the assumption that this will only happen during the commit
phase, and all that's gonna happen is that it will schedule another
batch, which is safe.
Fixes#17866Fixes#17878
This reverts commit 2f12b60701.
Co-authored-by: Rich Harris <rich.harris@vercel.com>
The combination of #17873 and #17805 resulted in a bad merge of the
latter because it wasn't up to date with main. This fixes it. No
changeset because not released yet.
---------
Co-authored-by: Rich Harris <rich.harris@vercel.com>
This simplifies the scheduling logic and will likely improve performance
in some cases. Previously, there was a global `queued_root_effects`
array, and we would cycle through the batch flushing logic as long as it
was non-empty. This was a very loosey-goosey approach that was
appropriate in the pre-async world, but has gradually become a source of
confusion.
Now, effects are scheduled within the context of a specific batch. The
lifecycle is more rigorous and debuggable. This opens the door to
explorations of alternative approaches, such as only scheduling effects
when we call `batch.flush()`, which _may_ be better than the eager
status quo.
The layout of the `Batch` class is extremely chaotic —
public/private/static fields/methods are all jumbled up together — and I
would like to get a grip of it. In the interests of minimising diff
noise that ought to be a follow-up rather than part of this PR.
### 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: Simon H <5968653+dummdidumm@users.noreply.github.com>
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>
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>
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.
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`
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`
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>
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>
## 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>
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>
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.
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.
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.
## 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>
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>
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
## 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>
## 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>
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>
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`
## 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>
tiny fix — just realised we're calling `this.apply()` (via
`this.activate()`) unnecessarily, since it will happen again immediately
after in `flush_effects`
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`
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`
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.
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`
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>
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.
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`
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@5.53.3
### Patch Changes
- fix: render `:catch` of `#await` block with correct key
([#17769](https://github.com/sveltejs/svelte/pull/17769))
- chore: pin aria-query@5.3.1
([#17772](https://github.com/sveltejs/svelte/pull/17772))
- fix: make string coercion consistent to `toString`
([#17774](https://github.com/sveltejs/svelte/pull/17774))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Closes#17758
### 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`
The only change between 5.3.1 and 5.3.2 is
2106d5e872
to support versions of Node before 4, with the cost of a minuscule but
pointless performance hit. This is a pretty stable library, and there
have been no further changes in the ensuing year and a half, so it seems
pretty safe to pin to the previous version.
### 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.
- [ ] 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`
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@5.53.2
### Patch Changes
- fix: update expressions on server deriveds
([#17767](https://github.com/sveltejs/svelte/pull/17767))
- fix: further obfuscate `node:crypto` import from overzealous static
analysis ([#17763](https://github.com/sveltejs/svelte/pull/17763))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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@5.53.1
### Patch Changes
- fix: handle shadowed function names correctly
([#17753](https://github.com/sveltejs/svelte/pull/17753))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Fixes#17750 (though the change that causes the issue only surfaced this
more general bug)
We were not adding the correct scope to function ids. Instead it was
part of the function body/params scope, which leads to bugs when the
function name is shadowed within the function.
Alternative to #17188. I prefer this syntax, it's lighter and feels much
more natural to me. For me it's less about commenting things _out_ than
about just, well... commenting — I frequently want to do this sort of
thing:
```svelte
<button
// when the user clicks the button, the thing should happen
onclick={doTheThing}
>click me</button>
```
One difference between this and #17188 is that this doesn't add a node
to the AST, just like comments in CSS/JS. Haven't decided if that's
desirable or not. I think it's more correct (it's an AST, not a CST;
HTML comments are different insofar as they _can_ represent 'real'
nodes) but it might be less convenient when (for example)
pretty-printing.
### 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>
This makes error boundaries run on the server if a new `onerror` handler
is passed to `render`. `onerror` can either synchronously or
asynchronously return a value. It should be a sanitized
JSON.stringify-able value so that it can be passed to the client for
hydration via a comment. `mount/hydrate` also get the `onerror`
property.
If no `onerror` is passed to `render` it will just throw just like
before, hence this is backwards compatible.
This work is important for SvelteKit to allow `+error.svelte` to make
use of them and in general to make boundaries properly work during SSR
(also see https://github.com/sveltejs/kit/issues/14398).
closes#15370
### 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: Rich Harris <rich.harris@vercel.com>
Fixes#17726
The problem was that the head effect had no "keep me around"-flag, which
it needs because its children are not guaranteed to be present
immediately - as shown in the related issue, where the child effect is
only created once async work has completed.
### 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`
Small tweak: except for `{#await ...}` blocks, which are a bit of an
anomaly, I'm pretty sure we _always_ want to deactivate the current
batch when unsetting context, otherwise it could incorrectly pick up
unrelated state changes. There might even be some subtle bugs lurking in
the system at present because we _don't_ always do 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.
- [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`
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@5.52.0
### Minor Changes
- feat: support TrustedHTML in `{@html}` expressions
([#17701](https://github.com/sveltejs/svelte/pull/17701))
### Patch Changes
- fix: repair dynamic component truthy/falsy hydration mismatches
([#17737](https://github.com/sveltejs/svelte/pull/17737))
- fix: re-run non-render-bound deriveds on the server
([#17674](https://github.com/sveltejs/svelte/pull/17674))
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
I tried to bring #14977 up-to-date but it's slipped too far. Also, I
wanted to try a slightly different approach.
In this PR, deriveds are memoized if they're created during render — in
other words if you have something like this...
```svelte
<script>
let thing = $derived(expensivelyComputeThing());
</script>
```
...`thing` will only be computed once. This seems correct since the
inputs should never change during render.
For deriveds created _outside_ render, we re-run the derived each time
it is accessed, which fixes#14954. This way, there's still _some_
overhead compared to how deriveds work in the browser (where they only
recompute when their dependencies have changed), but only in the rare
places where it is necessary.
There is one wrinkle: writable deriveds. On `main` these are just
regular old variables, which means they can be written to during render.
This PR currently preserves that behaviour, but I'm not sure it's
desirable. It prevents the values of non-render-bound deriveds from ever
updating, and makes no sense in the context of render-bound deriveds
since they shouldn't be changing during render _anyway_. So my
preference would be to disallow writes to deriveds on the server, but
I'm not sure if we would need to consider that a breaking change.
Draft because of that question, and also because I think we might be
able to tidy up some stuff around class fields.
- [x] figure out if we can delete some existing code around derived
class fields
- [x] figure out what to do about writable deriveds
- [x] add a test
### 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`
Abishek Raj R R
Nitin Sahu
Simon H
Paolo Ricciuti
Rich Harris
github-actions[bot]
Conduitry
Apoorv Darshan
dependabot[bot]
dev-miro26
Philip Breuer
Mathias Picker
Elliott Johnson
Maurício Kishi