First Component - accordion
Certainly! I'll explain the provided code in great detail, following the guidelines you've outlined. Let's start by showing the original code and then break it down step by step.
<script>
import { createAccordion, melt } from '@melt-ui/svelte';
const { elements: { root, item, trigger, content }, helpers: { isSelected } } = createAccordion();
</script>
<div use:melt={$root}>
<div use:melt={$item('item-1')}>
<h2><button use:melt={$trigger('item-1')}>Title</button></h2>
{#if $isSelected('item-1')}
<div use:melt={$content('item-1')}>Content</div>
{/if}
</div>
</div>
Now, let's break down this code and explain it in detail:
Importing and Setting Up
<script>
import { createAccordion, melt } from '@melt-ui/svelte';
const { elements: { root, item, trigger, content }, helpers: { isSelected } } = createAccordion();
</script>
This section sets up the necessary components for creating an accordion using the Melt UI library in Svelte.
We import two functions from '@melt-ui/svelte':
createAccordion
: This function creates the accordion functionality.melt
: This is a utility function used to apply Melt UI behavior to elements.
We call
createAccordion()
and use destructuring to extract several properties:elements
: Contains references to different parts of the accordion (root, item, trigger, content).helpers
: Provides utility functions, in this case,isSelected
.
Creating the Accordion Structure
<div use:melt={$root}>
<div use:melt={$item('item-1')}>
<h2><button use:melt={$trigger('item-1')}>Title</button></h2>
{#if $isSelected('item-1')}
<div use:melt={$content('item-1')}>Content</div>
{/if}
</div>
</div>
This section creates the HTML structure for the accordion:
The outermost
<div>
usesuse:melt={$root}
to apply the root accordion behavior.Inside, we have another
<div>
that represents an accordion item:use:melt={$item('item-1')}
applies item-specific behavior and identifies this as 'item-1'.
The accordion item contains:
A
<h2>
with a<button>
inside. This button acts as the trigger to expand/collapse the item.use:melt={$trigger('item-1')}
applies trigger behavior to the button for 'item-1'.
The content of the accordion item is conditionally rendered:
{#if $isSelected('item-1')}
checks if 'item-1' is currently selected (expanded).If true, it renders a
<div>
with the content.use:melt={$content('item-1')}
applies content-specific behavior to this div.
Key Concepts
Reactive Statements: The
$
prefix (e.g.,$root
,$isSelected
) indicates these are reactive statements in Svelte. They will automatically update when their underlying values change.Conditional Rendering: The
{#if}
block ensures that the content is only rendered when the item is selected, improving performance by not rendering hidden content.Accessibility: Melt UI handles much of the accessibility concerns for accordions, such as proper ARIA attributes and keyboard navigation.
This example shows only one accordion item. In a real-world scenario, you'd likely have multiple items, each with a unique identifier.
Minimal Working Example
Here's a minimal working example of a simple accordion with two items:
<script>
import { createAccordion, melt } from '@melt-ui/svelte';
const { elements: { root, item, trigger, content }, helpers: { isSelected } } = createAccordion();
</script>
<div use:melt={$root}>
{#each ['item-1', 'item-2'] as id}
<div use:melt={$item(id)}>
<button use:melt={$trigger(id)}>Item {id.slice(-1)}</button>
{#if $isSelected(id)}
<div use:melt={$content(id)}>Content for item {id.slice(-1)}</div>
{/if}
</div>
{/each}
</div>
This example demonstrates how to create a simple accordion with two items using a loop. It showcases the core functionality while keeping the code concise and easy to understand.
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