@ -10,7 +10,7 @@ It's the last "What's new in Svelte" of the year and there's lots to celebrate!
## New features & impactful bug fixes
1. `$$props`, `$$restProps`, and `$$slots` are all now supported in custom web components (**3.29.5**, [Example](https://svelte.dev/repl/ad8e6f39cd20403dacd1be84d71e498d?version=3.29.5)) and `slot` components now support spread props: `<slot {...foo} />` (**3.30.0**)
2. A new `hasContext` lifecycle function makes it easy to check whether a `key` has been set in the context of a parent component (**3.30.0** &**3.30.1**, [Docs](https://svelte.dev/docs#hasContext))
2. A new `hasContext` lifecycle function makes it easy to check whether a `key` has been set in the context of a parent component (**3.30.0** &**3.30.1**, [Docs](https://svelte.dev/docs#run-time-svelte-hascontext))
3. There is now a new `SvelteComponentTyped` class which makes it easier to add strongly typed components that extend base Svelte components. Component library and framework authors rejoice! An example: `export class YourComponent extends SvelteComponentTyped<{aProp: boolean}, {click: MouseEvent}, {default: {aSlot: string}}> {}` (**3.31.0**, [RFC](https://github.com/sveltejs/rfcs/pull/37))
4. Transitions within `{:else}` blocks should now complete successfully (**3.29.5**, [Example](https://svelte.dev/repl/49cef205e5da459594ef2eafcbd41593?version=3.29.5))
5. Svelte now includes an export map, which explicitly states which files can be imported from its npm package (**3.29.5** with some fixes in **3.29.6**, **3.29.7** and **3.30.0**)
@ -10,13 +10,13 @@ Lots to cover this month with releases from across the Svelte ecosystem. Most im
Let's dive into the news 🐬
## What's new in `sveltejs/svelte`
* SSR store handling has been reworked to subscribe and unsubscribe as in DOM mode. SSR stores should work much more consistently now (**3.31.2**, see [custom stores](https://svelte.dev/examples#custom-stores) and [Server-side component API ](https://svelte.dev/docs#Server-side_component_API))
* SSR store handling has been reworked to subscribe and unsubscribe as in DOM mode. SSR stores should work much more consistently now (**3.31.2**, see [custom stores](https://svelte.dev/examples#custom-stores) and [Server-side component API ](https://svelte.dev/docs#run-time-server-side-component-api))
* Multiple instances of the same action are now allowed on an element (**3.32.0**, [example](https://svelte.dev/repl/01a14375951749dab9579cb6860eccde?version=3.32.0))
* The new `foreign` namespace should make it easier for alternative compile targets (like Svelte Native and SvelteGUI) by disabling certain HTML5-specific behaviour and checks (**3.32.0**, [more info](https://github.com/sveltejs/svelte/pull/5652))
* Support for inline comment sourcemaps in code from preprocessors (**3.32.0**)
* Destructured defaults are now allowed to refer to other variables (**3.33.0**, [example](https://svelte.dev/repl/0ee7227e1b45465b9b47d7a5ae2d1252?version=3.33.0))
* Custom elements will now call `onMount` functions when connecting and clean up when disconnecting (**3.33.0**, checkout [this PR](https://github.com/sveltejs/svelte/pull/4522) for an interesting conversation on how folks are using Svelte with Web Components)
* A `cssHash` option has been added to the compiler options to control the classname used for CSS scoping (**3.34.0**, [docs](https://svelte.dev/docs#svelte_compile))
* A `cssHash` option has been added to the compiler options to control the classname used for CSS scoping (**3.34.0**, [docs](https://svelte.dev/docs#compile-time-svelte-compile))
* Continued improvement to Typescript definitions
For a complete list of changes, including bug fixes and links to PRs, check out [the CHANGELOG](https://github.com/sveltejs/svelte/blob/master/CHANGELOG.md)
@ -13,7 +13,7 @@ Two projects that have been months (even years) in the making have made their wa
Want to learn more about how to get started, what's different compared to Sapper, new features and migration paths? Check out this week's [episode of Svelte Radio](https://www.svelteradio.com/episodes/svelte-kit-public-beta) for a deep dive with Antony, Kev and Swyx.
## New in Svelte & Language Tools
- Slotted components, including `<svelte:fragment slot="...">` lets component consumers target specific slots with rich content (**Svelte 3.35.0, Language Tools [104.5.0](https://github.com/sveltejs/language-tools/releases/tag/extensions-104.5.0)**, check out the [docs](https://svelte.dev/docs#svelte_fragment) and the [tutorial](https://svelte.dev/tutorial/svelte-fragment))
- Slotted components, including `<svelte:fragment slot="...">` lets component consumers target specific slots with rich content (**Svelte 3.35.0, Language Tools [104.5.0](https://github.com/sveltejs/language-tools/releases/tag/extensions-104.5.0)**, check out the [docs](https://svelte.dev/docs#template-syntax-svelte-fragment) and the [tutorial](https://svelte.dev/tutorial/svelte-fragment))
- Linked editing now works for HTML in Svelte files (**Language Tools, [104.6.0](https://github.com/sveltejs/language-tools/releases/tag/extensions-104.6.0)**)
- Type definitions `svelte.d.ts` are now resolved in order, allowing library authors to ship type definitions with their svelte components (**Language Tools, [104.7.0](https://github.com/sveltejs/language-tools/releases/tag/extensions-104.7.0)**)
- [vite-plugin-svelte](https://github.com/sveltejs/vite-plugin-svelte) is available for general use of Svelte in Vite. `npm init @vitejs/app` includes Svelte options using this plugin.
@ -28,7 +28,7 @@ A `<script>` block contains JavaScript that runs when a component instance is cr
---
Svelte uses the `export` keyword to mark a variable declaration as a *property* or *prop*, which means it becomes accessible to consumers of the component (see the section on [attributes and props](docs#Attributes_and_props) for more information).
Svelte uses the `export` keyword to mark a variable declaration as a *property* or *prop*, which means it becomes accessible to consumers of the component (see the section on [attributes and props](docs#template-syntax-attributes-and-props) for more information).
```sv
<script>
@ -44,7 +44,7 @@ Svelte uses the `export` keyword to mark a variable declaration as a *property*
You can specify a default initial value for a prop. It will be used if the component's consumer doesn't specify the prop on the component (or if its initial value is `undefined`) when instantiating the component. Note that whenever a prop is removed by the consumer, its value is set to `undefined` rather than the initial value.
In development mode (see the [compiler options](docs#svelte_compile)), a warning will be printed if no default initial value is provided and the consumer does not specify a value. To squelch this warning, ensure that a default initial value is specified, even if it is `undefined`.
In development mode (see the [compiler options](docs#compile-time-svelte-compile)), a warning will be printed if no default initial value is provided and the consumer does not specify a value. To squelch this warning, ensure that a default initial value is specified, even if it is `undefined`.
```sv
<script>
@ -57,7 +57,7 @@ In development mode (see the [compiler options](docs#svelte_compile)), a warning
If you export a `const`, `class` or `function`, it is readonly from outside the component. Function *expressions* are valid props, however.
Readonly props can be accessed as properties on the element, tied to the component using [`bind:this` syntax](docs#bind_element).
Readonly props can be accessed as properties on the element, tied to the component using [`bind:this` syntax](docs#template-syntax-element-directives-bind-element).
```sv
<script>
@ -191,7 +191,7 @@ If a statement consists entirely of an assignment to an undeclared variable, Sve
---
A *store* is an object that allows reactive access to a value via a simple *store contract*. The [`svelte/store` module](docs#svelte_store) contains minimal store implementations which fulfil this contract.
A *store* is an object that allows reactive access to a value via a simple *store contract*. The [`svelte/store` module](docs#run-time-svelte-store) contains minimal store implementations which fulfil this contract.
Any time you have a reference to a store, you can access its value inside a component by prefixing it with the `$` character. This causes Svelte to declare the prefixed variable, subscribe to the store at component initialization and unsubscribe when appropriate.
@ -222,7 +222,7 @@ Local variables (that do not represent store values) must *not* have a `$` prefi
You can create your own stores without relying on [`svelte/store`](docs#svelte_store), by implementing the *store contract*:
You can create your own stores without relying on [`svelte/store`](docs#run-time-svelte-store), by implementing the *store contract*:
1. A store must contain a `.subscribe` method, which must accept as its argument a subscription function. This subscription function must be immediately and synchronously called with the store's current value upon calling `.subscribe`. All of a store's active subscription functions must later be synchronously called whenever the store's value changes.
2. The `.subscribe` method must return an unsubscribe function. Calling an unsubscribe function must stop its subscription, and its corresponding subscription function must not be called again by the store.
@ -241,7 +241,7 @@ You can `export` bindings from this block, and they will become exports of the c
You cannot `export default`, since the default export is the component itself.
> Variables defined in `module` scripts are not reactive — reassigning them will not trigger a rerender even though the variable itself will update. For values shared between multiple components, consider using a [store](docs#svelte_store).
> Variables defined in `module` scripts are not reactive — reassigning them will not trigger a rerender even though the variable itself will update. For values shared between multiple components, consider using a [store](docs#run-time-svelte-store).
@ -929,7 +929,7 @@ The `transition:` directive indicates a *bidirectional* transition, which means
{/if}
```
> By default intro transitions will not play on first render. You can modify this behaviour by setting `intro: true` when you [create a component](docs#Client-side_component_API).
> By default intro transitions will not play on first render. You can modify this behaviour by setting `intro: true` when you [create a component](docs#run-time-client-side-component-api).
##### Transition parameters
@ -1148,9 +1148,9 @@ DOMRect {
---
An animation is triggered when the contents of a [keyed each block](docs#each) are re-ordered. Animations do not run when an element is added or removed, only when the index of an existing data item within the each block changes. Animate directives must be on an element that is an *immediate* child of a keyed each block.
An animation is triggered when the contents of a [keyed each block](docs#template-syntax-each) are re-ordered. Animations do not run when an element is added or removed, only when the index of an existing data item within the each block changes. Animate directives must be on an element that is an *immediate* child of a keyed each block.
Animations can be used with Svelte's [built-in animation functions](docs#svelte_animate) or [custom animation functions](docs#Custom_animation_functions).
Animations can be used with Svelte's [built-in animation functions](docs#run-time-svelte-animate) or [custom animation functions](docs#template-syntax-element-directives-animate-fn-custom-animation-functions).
```sv
<!-- When `list` is reordered the animation will run-->
@ -1249,7 +1249,7 @@ A custom animation function can also return a `tick` function, which is called *
### Component directives
#### [on:*eventname*](on_component_event)
#### on:*eventname*
```sv
on:eventname={handler}
@ -1257,7 +1257,7 @@ on:eventname={handler}
---
Components can emit events using [createEventDispatcher](docs#createEventDispatcher), or by forwarding DOM events. Listening for component events looks the same as listening for DOM events:
Components can emit events using [createEventDispatcher](docs#run-time-svelte-createeventdispatcher), or by forwarding DOM events. Listening for component events looks the same as listening for DOM events:
```sv
<SomeComponenton:whatever={handler}/>
@ -1271,7 +1271,7 @@ As with DOM events, if the `on:` directive is used without a value, the componen
<SomeComponenton:whatever/>
```
#### [--style-props](style_props)
#### --style-props
```sv
--style-props="anycssvalue"
@ -1340,7 +1340,7 @@ Or override it at the consumer level:
<Slider--rail-color="goldenrod"/>
```
#### [bind:*property*](bind_component_property)
#### bind:*property*
```sv
bind:property={variable}
@ -1354,7 +1354,7 @@ You can bind to component props using the same syntax as for elements.
<Keypadbind:value={pin}/>
```
#### [bind:this](bind_component)
#### bind:this
```sv
bind:this={component_instance}
@ -1410,7 +1410,7 @@ The content is exposed in the child component using the `<slot>` element, which
</Widget>
```
#### [`<slot name="`*name*`">`](slot_name)
#### `<slot name="`*name*`">`
---
@ -1453,7 +1453,7 @@ In order to place content in a slot without using a wrapper element, you can use
```
#### [`$$slots`](slots_object)
#### `$$slots`
---
@ -1479,7 +1479,7 @@ Note that explicitly passing in an empty named slot will add that slot's name to
</Card>
```
#### [`<slot key={`*value*`}>`](slot_let)
#### `<slot key={`*value*`}>`
---
@ -1617,7 +1617,7 @@ All except `scrollX` and `scrollY` are readonly.
---
Similarly to `<svelte:window>`, this element allows you to add listeners to events on `document.body`, such as `mouseenter` and `mouseleave`, which don't fire on `window`. It also lets you use [actions](docs#use_action) on the `<body>` element.
Similarly to `<svelte:window>`, this element allows you to add listeners to events on `document.body`, such as `mouseenter` and `mouseleave`, which don't fire on `window`. It also lets you use [actions](docs#template-syntax-element-directives-use-action) on the `<body>` element.
`<svelte:body>` also has to appear at the top level of your component.
@ -1657,7 +1657,7 @@ As with `<svelte:window>` and `<svelte:body>`, this element has to appear at the
---
The `<svelte:options>` element provides a place to specify per-component compiler options, which are detailed in the [compiler section](docs#svelte_compile). The possible options are:
The `<svelte:options>` element provides a place to specify per-component compiler options, which are detailed in the [compiler section](docs#compile-time-svelte-compile). The possible options are:
* `immutable={true}` — you never use mutable data, so the compiler can do simple referential equality checks to determine if values have changed
* `immutable={false}` — the default. Svelte will be more conservative about whether or not mutable objects have changed
@ -1672,7 +1672,7 @@ The `<svelte:options>` element provides a place to specify per-component compile
### `<svelte:fragment>`
The `<svelte:fragment>` element allows you to place content in a [named slot](docs#slot_name) without wrapping it in a container DOM element. This keeps the flow layout of your document intact.
The `<svelte:fragment>` element allows you to place content in a [named slot](docs#template-syntax-slot-slot-name) without wrapping it in a container DOM element. This keeps the flow layout of your document intact.
The `onMount` function schedules a callback to run as soon as the component has been mounted to the DOM. It must be called during the component's initialisation (but doesn't need to live *inside* the component; it can be called from an external module).
`onMount` does not run inside a [server-side component](docs#Server-side_component_API).
`onMount` does not run inside a [server-side component](docs#run-time-server-side-component-api).
Creates an event dispatcher that can be used to dispatch [component events](docs#on_component_event). Event dispatchers are functions that can take two arguments: `name` and `detail`.
Creates an event dispatcher that can be used to dispatch [component events](docs#template-syntax-component-directives-on-component-event). Event dispatchers are functions that can take two arguments: `name` and `detail`.
Component events created with `createEventDispatcher` create a [CustomEvent](https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent). These events do not [bubble](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events#Event_bubbling_and_capture) and are not cancellable with `event.preventDefault()`. The `detail` argument corresponds to the [CustomEvent.detail](https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/detail) property and can contain any type of data.
@ -256,11 +256,11 @@ Events dispatched from child components can be listened to in their parent. Any
### `svelte/store`
The `svelte/store` module exports functions for creating [readable](docs#readable), [writable](docs#writable) and [derived](docs#derived) stores.
The `svelte/store` module exports functions for creating [readable](docs#run-time-svelte-store-readable), [writable](docs#run-time-svelte-store-writable) and [derived](docs#run-time-svelte-store-derived) stores.
Keep in mind that you don't *have* to use these functions to enjoy the [reactive `$store` syntax](docs#4_Prefix_stores_with_$_to_access_their_values) in your components. Any object that correctly implements `.subscribe`, unsubscribe, and (optionally) `.set` is a valid store, and will work both with the special syntax, and with Svelte's built-in [`derived` stores](docs#derived).
Keep in mind that you don't *have* to use these functions to enjoy the [reactive `$store` syntax](docs#component-format-script-4-prefix-stores-with-$-to-access-their-values) in your components. Any object that correctly implements `.subscribe`, unsubscribe, and (optionally) `.set` is a valid store, and will work both with the special syntax, and with Svelte's built-in [`derived` stores](docs#run-time-svelte-store-derived).
This makes it possible to wrap almost any other reactive state handling library for use in Svelte. Read more about the [store contract](docs#Store_contract) to see what a correct implementation looks like.
This makes it possible to wrap almost any other reactive state handling library for use in Svelte. Read more about the [store contract](docs#component-format-script-4-prefix-stores-with-$-to-access-their-values-store-contract) to see what a correct implementation looks like.
#### `writable`
@ -446,7 +446,7 @@ Tweened stores update their values over a fixed duration. The following options
* `delay` (`number`, default 0) — milliseconds before starting
* `duration` (`number`, default 400) — milliseconds the tween lasts
`store.set` and `store.update` can accept a second `options` argument that will override the options passed in upon instantiation.
@ -537,7 +537,7 @@ A `spring` store gradually changes to its target value based on its `stiffness`
---
As with [`tweened`](docs#tweened) stores, `set` and `update` return a Promise that resolves if the spring settles. The `store.stiffness` and `store.damping` properties can be changed while the spring is in motion, and will take immediate effect.
As with [`tweened`](docs#run-time-svelte-motion-tweened) stores, `set` and `update` return a Promise that resolves if the spring settles. The `store.stiffness` and `store.damping` properties can be changed while the spring is in motion, and will take immediate effect.
Both `set` and `update` can take a second argument — an object with `hard` or `soft` properties. `{ hard: true }` sets the target value immediately; `{ soft: n }` preserves existing momentum for `n` seconds before settling. `{ soft: true }` is equivalent to `{ soft: 0.5 }`.
@ -565,7 +565,7 @@ $: $size = big ? 100 : 10;
### `svelte/transition`
The `svelte/transition` module exports seven functions: `fade`, `blur`, `fly`, `slide`, `scale`, `draw` and `crossfade`. They are for use with Svelte [`transitions`](docs#transition_fn).
The `svelte/transition` module exports seven functions: `fade`, `blur`, `fly`, `slide`, `scale`, `draw` and `crossfade`. They are for use with Svelte [`transitions`](docs#template-syntax-element-directives-transition-fn).
#### `fade`
@ -587,7 +587,7 @@ Animates the opacity of an element from 0 to the current opacity for `in` transi
* `delay` (`number`, default 0) — milliseconds before starting
* `duration` (`number`, default 400) — milliseconds the transition lasts
* `easing` (`function`, default `linear`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `linear`) — an [easing function](docs#run-time-svelte-easing)
You can see the `fade` transition in action in the [transition tutorial](tutorial/transition).
@ -623,7 +623,7 @@ Animates a `blur` filter alongside an element's opacity.
* `delay` (`number`, default 0) — milliseconds before starting
* `duration` (`number`, default 400) — milliseconds the transition lasts
* `easing` (`function`, default `cubicInOut`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `cubicInOut`) — an [easing function](docs#run-time-svelte-easing)
* `opacity` (`number`, default 0) - the opacity value to animate out to and in from
* `amount` (`number`, default 5) - the size of the blur in pixels
@ -659,7 +659,7 @@ Animates the x and y positions and the opacity of an element. `in` transitions a
* `delay` (`number`, default 0) — milliseconds before starting
* `duration` (`number`, default 400) — milliseconds the transition lasts
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#run-time-svelte-easing)
* `x` (`number`, default 0) - the x offset to animate out to and in from
* `y` (`number`, default 0) - the y offset to animate out to and in from
* `opacity` (`number`, default 0) - the opacity value to animate out to and in from
@ -699,7 +699,7 @@ Slides an element in and out.
* `delay` (`number`, default 0) — milliseconds before starting
* `duration` (`number`, default 400) — milliseconds the transition lasts
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#run-time-svelte-easing)
```sv
<script>
@ -734,7 +734,7 @@ Animates the opacity and scale of an element. `in` transitions animate from an e
* `delay` (`number`, default 0) — milliseconds before starting
* `duration` (`number`, default 400) — milliseconds the transition lasts
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#run-time-svelte-easing)
* `start` (`number`, default 0) - the scale value to animate out to and in from
* `opacity` (`number`, default 0) - the opacity value to animate out to and in from
@ -772,7 +772,7 @@ Animates the stroke of an SVG element, like a snake in a tube. `in` transitions
* `delay` (`number`, default 0) — milliseconds before starting
* `speed` (`number`, default undefined) - the speed of the animation, see below.
* `easing` (`function`, default `cubicInOut`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `cubicInOut`) — an [easing function](docs#run-time-svelte-easing)
The `speed` parameter is a means of setting the duration of the transition relative to the path's length. It is a modifier that is applied to the length of the path: `duration = length / speed`. A path that is 1000 pixels with a speed of 1 will have a duration of `1000ms`, setting the speed to `0.5` will double that duration and setting it to `2` will halve it.
@ -799,7 +799,7 @@ The `speed` parameter is a means of setting the duration of the transition relat
#### `crossfade`
The `crossfade` function creates a pair of [transitions](docs#transition_fn) called `send` and `receive`. When an element is 'sent', it looks for a corresponding element being 'received', and generates a transition that transforms the element to its counterpart's position and fades it out. When an element is 'received', the reverse happens. If there is no counterpart, the `fallback` transition is used.
The `crossfade` function creates a pair of [transitions](docs#template-syntax-element-directives-transition-fn) called `send` and `receive`. When an element is 'sent', it looks for a corresponding element being 'received', and generates a transition that transforms the element to its counterpart's position and fades it out. When an element is 'received', the reverse happens. If there is no counterpart, the `fallback` transition is used.
---
@ -807,8 +807,8 @@ The `crossfade` function creates a pair of [transitions](docs#transition_fn) cal
* `delay` (`number`, default 0) — milliseconds before starting
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#svelte_easing)
* `fallback` (`function`) — A fallback [transition](docs#transition_fn) to use for send when there is no matching element being received, and for receive when there is no element being sent.
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#run-time-svelte-easing)
* `fallback` (`function`) — A fallback [transition](docs#template-syntax-element-directives-transition-fn) to use for send when there is no matching element being received, and for receive when there is no element being sent.
```sv
<script>
@ -831,7 +831,7 @@ The `crossfade` function creates a pair of [transitions](docs#transition_fn) cal
### `svelte/animate`
The `svelte/animate` module exports one function for use with Svelte [animations](docs#animate_fn).
The `svelte/animate` module exports one function for use with Svelte [animations](docs#template-syntax-element-directives-animate-fn).
#### `flip`
@ -845,7 +845,7 @@ The `flip` function calculates the start and end position of an element and anim
* `delay` (`number`, default 0) — milliseconds before starting
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#svelte_easing)
* `easing` (`function`, default `cubicOut`) — an [easing function](docs#run-time-svelte-easing)
`duration` can be provided as either:
@ -961,7 +961,7 @@ Existing children of `target` are left where they are.
---
The `hydrate` option instructs Svelte to upgrade existing DOM (usually from server-side rendering) rather than creating new elements. It will only work if the component was compiled with the [`hydratable: true` option](docs#svelte_compile). Hydration of `<head>` elements only works properly if the server-side rendering code was also compiled with `hydratable: true`, which adds a marker to each element in the `<head>` so that the component knows which elements it's responsible for removing during hydration.
The `hydrate` option instructs Svelte to upgrade existing DOM (usually from server-side rendering) rather than creating new elements. It will only work if the component was compiled with the [`hydratable: true` option](docs#compile-time-svelte-compile). Hydration of `<head>` elements only works properly if the server-side rendering code was also compiled with `hydratable: true`, which adds a marker to each element in the `<head>` so that the component knows which elements it's responsible for removing during hydration.
Whereas children of `target` are normally left alone, `hydrate: true` will cause any children to be removed. For that reason, the `anchor` option cannot be used alongside `hydrate: true`.
@ -1045,7 +1045,7 @@ app.count += 1;
---
Svelte components can also be compiled to custom elements (aka web components) using the `customElement: true` compiler option. You should specify a tag name for the component using the `<svelte:options>` [element](docs#svelte_options).
Svelte components can also be compiled to custom elements (aka web components) using the `customElement: true` compiler option. You should specify a tag name for the component using the `<svelte:options>` [element](docs#template-syntax-svelte-options).
```sv
<svelte:optionstag="my-element"/>
@ -1082,7 +1082,7 @@ document.body.innerHTML = `
---
By default, custom elements are compiled with `accessors: true`, which means that any [props](docs#Attributes_and_props) are exposed as properties of the DOM element (as well as being readable/writable as attributes, where possible).
By default, custom elements are compiled with `accessors: true`, which means that any [props](docs#template-syntax-attributes-and-props) are exposed as properties of the DOM element (as well as being readable/writable as attributes, where possible).
To prevent this, add `accessors={false}` to `<svelte:options>`.
@ -1119,7 +1119,7 @@ Unlike client-side components, server-side components don't have a lifespan afte
A server-side component exposes a `render` method that can be called with optional props. It returns an object with `head`, `html`, and `css` properties, where `head` contains the contents of any `<svelte:head>` elements encountered.
You can import a Svelte component directly into Node using [`svelte/register`](docs#svelte_register).
You can import a Svelte component directly into Node using [`svelte/register`](docs#run-time-svelte-register).
> It's possible to derive a store from multiple inputs, and to explicitly `set` a value instead of returning it (which is useful for deriving values asynchronously). Consult the [API reference](docs#derived) for more information.
> It's possible to derive a store from multiple inputs, and to explicitly `set` a value instead of returning it (which is useful for deriving values asynchronously). Consult the [API reference](docs#run-time-svelte-store-derived) for more information.
Rich Harris
3 years ago
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GitHub