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fix: Carousel navigation buttons and scrolling functionality #2326

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fix: Carousel navigation buttons and scrolling functionality #2326

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3e4d688
Scroll fixed and enabled buttons
fyzanshaik Aug 27, 2025
b11b0af
prettier format
fyzanshaik Aug 27, 2025
f40a406
Merge branch 'main' into doc-2122-carousel-scroll-fix
ebenezerdon Sep 11, 2025
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36 changes: 26 additions & 10 deletions src/lib/components/Carousel.svelte
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Original file line number Diff line number Diff line change
Expand Up @@ -11,20 +11,20 @@
}
const { size = 'default', gap = 32, header, children }: Props = $props();
let scroll = 0;
function calculateScrollAmount(prev = false) {
if (!carousel) return 0;
const direction = prev ? -1 : 1;
const carouselSize = carousel?.clientWidth;
const childSize = (carousel.childNodes[0] as HTMLUListElement)?.clientWidth + gap;
const carouselSize = carousel.clientWidth;
scroll = scroll || carouselSize;
const firstChild = carousel.querySelector('li') as HTMLElement;
if (!firstChild) return 0;
const childSize = firstChild.offsetWidth + gap;
const numberOfItems = Math.floor(carouselSize / childSize);
const overflow = scroll % childSize;
const amount = numberOfItems * childSize - overflow * direction;
scroll += amount * direction;
return amount * direction;
return numberOfItems * childSize * direction;
}
Comment on lines 15 to 28
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🛠️ Refactor suggestion

⚠️ Potential issue

Fix zero-step bug when item is wider than viewport; prefer direct-child query and clamp page size.

If firstChild.offsetWidth + gap > carousel.clientWidth, Math.floor(...) becomes 0 so scrollBy({ left: 0 }) does nothing and buttons appear broken on narrow viewports. Also, querySelector('li') may match nested list items; use :scope > li.

-        const firstChild = carousel.querySelector('li') as HTMLElement;
+        const firstChild = carousel.querySelector(':scope > li') as HTMLElement | null;
         if (!firstChild) return 0;

-        const childSize = firstChild.offsetWidth + gap;
-        const numberOfItems = Math.floor(carouselSize / childSize);
-
-        return numberOfItems * childSize * direction;
+        const childSize = firstChild.offsetWidth + gap;
+        const itemsPerPage = Math.max(1, Math.floor(carouselSize / childSize));
+        return itemsPerPage * childSize * direction;

Optional typings outside this hunk (helps TS and DOM correctness):

// line 4
let carousel: HTMLUListElement;
// line 15
function calculateScrollAmount(prev = false): number {
🤖 Prompt for AI Agents 
In src/lib/components/Carousel.svelte around lines 15 to 28, the calculation can
return 0 when an item (offsetWidth + gap) is larger than the carousel viewport
and querySelector('li') may match nested items; update the function to select
direct children via carousel.querySelector(':scope > li') and compute
numberOfItems as Math.max(1, Math.floor(carouselSize / childSize)) (so we always
scroll at least one item), ensure the function returns a number type, and
optionally add typing for carousel as HTMLUListElement and the function
signature as calculateScrollAmount(prev = false): number.

function next() {
Expand All @@ -44,9 +44,19 @@
let isStart = $state(true);
function handleScroll() {
if (!carousel) return;
isStart = carousel.scrollLeft <= 0;
isEnd = Math.ceil(carousel.scrollLeft + carousel.offsetWidth) >= carousel.scrollWidth;
isEnd = Math.ceil(carousel.scrollLeft + carousel.offsetWidth) >= carousel.scrollWidth - 1;
}
$effect(() => {
if (carousel) {
setTimeout(() => {
handleScroll();
}, 0);
}
});
</script>

<div>
Expand All @@ -66,7 +76,7 @@
<button
class="web-icon-button cursor-pointer"
aria-label="Move carousel forward"
disabled
disabled={isEnd}
onclick={next}
>
<span class="web-icon-arrow-right" aria-hidden="true"></span>
Expand All @@ -82,6 +92,12 @@
style:gap="{gap}px"
bind:this={carousel}
onscroll={handleScroll}
onwheel={(e) => {
if (e.deltaY !== 0) {
e.preventDefault();
carousel.scrollLeft += e.deltaY;
}
}}
>
{@render children()}
</ul>
Expand Down