@networkpro/web
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This package powers the official web presence of Network Pro Strategies — a research- and infrastructure-focused technology initiative working across cybersecurity, digital systems, and privacy.
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```svelte
<!--- copy: false --->
{#snippet name()}...{/snippet}
```
```svelte
<!--- copy: false --->
{#snippet name(param1, param2, paramN)}...{/snippet}
```
Snippets, and [render tags](@render), are a way to create reusable chunks of markup inside your components. Instead of writing duplicative code like this...
```svelte
{#each images as image}
{#if image.href}
<a href={image.href}>
<figure>
<img src={image.src} alt={image.caption} width={image.width} height={image.height} />
<figcaption>{image.caption}</figcaption>
</figure>
</a>
{:else}
<figure>
<img src={image.src} alt={image.caption} width={image.width} height={image.height} />
<figcaption>{image.caption}</figcaption>
</figure>
{/if}
{/each}
```
...you can write this:
```svelte
{#snippet figure(image)}
<figure>
<img src={image.src} alt={image.caption} width={image.width} height={image.height} />
<figcaption>{image.caption}</figcaption>
</figure>
{/snippet}
{#each images as image}
{#if image.href}
<a href={image.href}>
{@render figure(image)}
</a>
{:else}
{@render figure(image)}
{/if}
{/each}
```
Like function declarations, snippets can have an arbitrary number of parameters, which can have default values, and you can destructure each parameter. You cannot use rest parameters, however.
## Snippet scope
Snippets can be declared anywhere inside your component. They can reference values declared outside themselves, for example in the `<script>` tag or in `{#each ...}` blocks (demo...
```svelte
<script>
let { message = `it's great to see you!` } = $props();
</script>
{#snippet hello(name)}
<p>hello {name}! {message}!</p>
{/snippet}
{@render hello('alice')}
{@render hello('bob')}
```
...and they are 'visible' to everything in the same lexical scope (i.e. siblings, and children of those siblings):
```svelte
<div>
{#snippet x()}
{#snippet y()}...{/snippet}
<!-- this is fine -->
{@render y()}
{/snippet}
<!-- this will error, as `y` is not in scope -->
{@render y()}
</div>
<!-- this will also error, as `x` is not in scope -->
{@render x()}
```
Snippets can reference themselves and each other (demo:
```svelte
{#snippet blastoff()}
<span>🚀</span>
{/snippet}
{#snippet countdown(n)}
{#if n > 0}
<span>{n}...</span>
{@render countdown(n - 1)}
{:else}
{@render blastoff()}
{/if}
{/snippet}
{@render countdown(10)}
```
## Passing snippets to components
### Explicit props
Within the template, snippets are values just like any other. As such, they can be passed to components as props (demo:
```svelte
<script>
import Table from './Table.svelte';
const fruits = [
{ name: 'apples', qty: 5, price: 2 },
{ name: 'bananas', qty: 10, price: 1 },
{ name: 'cherries', qty: 20, price: 0.5 },
];
</script>
{#snippet header()}
<th>fruit</th>
<th>qty</th>
<th>price</th>
<th>total</th>
{/snippet}
{#snippet row(d)}
<td>{d.name}</td>
<td>{d.qty}</td>
<td>{d.price}</td>
<td>{d.qty * d.price}</td>
{/snippet}
<Table data={fruits} {header} {row} />
```
Think about it like passing content instead of data to a component. The concept is similar to slots in web components.
### Implicit props
As an authoring convenience, snippets declared directly _inside_ a component implicitly become props _on_ the component (demo:
```svelte
<!-- this is semantically the same as the above -->
<Table data={fruits}>
{#snippet header()}
<th>fruit</th>
<th>qty</th>
<th>price</th>
<th>total</th>
{/snippet}
{#snippet row(d)}
<td>{d.name}</td>
<td>{d.qty}</td>
<td>{d.price}</td>
<td>{d.qty * d.price}</td>
{/snippet}
</Table>
```
### Implicit `children` snippet
Any content inside the component tags that is _not_ a snippet declaration implicitly becomes part of the `children` snippet (demo:
```svelte
<!--- file: App.svelte --->
<Button>click me</Button>
```
```svelte
<!--- file: Button.svelte --->
<script>
let { children } = $props();
</script>
<!-- result will be <button>click me</button> -->
<button>{@render children()}</button>
```
> [!NOTE] Note that you cannot have a prop called `children` if you also have content inside the component — for this reason, you should avoid having props with that name
### Optional snippet props
You can declare snippet props as being optional. You can either use optional chaining to not render anything if the snippet isn't set...
```svelte
<script>
let { children } = $props();
</script>
{@render children?.()}
```
...or use an `#if` block to render fallback content:
```svelte
<script>
let { children } = $props();
</script>
{#if children}
{@render children()}
{:else}
fallback content
{/if}
```
## Typing snippets
Snippets implement the `Snippet` interface imported from `'svelte'`:
```svelte
<script lang="ts">
import type { Snippet } from 'svelte';
interface Props {
data: any[];
children: Snippet;
row: Snippet<[any]>;
}
let { data, children, row }: Props = $props();
</script>
```
With this change, red squigglies will appear if you try and use the component without providing a `data` prop and a `row` snippet. Notice that the type argument provided to `Snippet` is a tuple, since snippets can have multiple parameters.
We can tighten things up further by declaring a generic, so that `data` and `row` refer to the same type:
```svelte
<script lang="ts" generics="T">
import type { Snippet } from 'svelte';
let {
data,
children,
row,
}: {
data: T[];
children: Snippet;
row: Snippet<[T]>;
} = $props();
</script>
```
## Exporting snippets
Snippets declared at the top level of a `.svelte` file can be exported from a `<script module>` for use in other components, provided they don't reference any declarations in a non-module `<script>` (whether directly or indirectly, via other snippets) (demo:
```svelte
<script module>
export { add };
</script>
{#snippet add(a, b)}
{a} + {b} = {a + b}
{/snippet}
```
> [!NOTE]
> This requires Svelte 5.5.0 or newer
## Programmatic snippets
Snippets can be created programmatically with the [`createRawSnippet`](svelte#createRawSnippet) API. This is intended for advanced use cases.
## Snippets and slots
In Svelte 4, content can be passed to components using [slots](legacy-slots). Snippets are more powerful and flexible, and so slots have been deprecated in Svelte 5.