125 lines
3.8 KiB
Markdown
125 lines
3.8 KiB
Markdown
---
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title: Image gallery with horizontal scroll
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tags: visual,interactivity
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expertise: advanced
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cover: blog_images/flower-portrait-5.jpg
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firstSeen: 2022-05-01T05:00:00-04:00
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---
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Creates a horizontally scrollable image gallery.
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- Position the `.thumbnails` at the bottom of the container using `position: absolute`.
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- Use `scroll-snap-type: x mandatory` and `overscroll-behavior-x: contain` to create a snap effect on horizontal scroll. Snap elements to the start of the container using `scroll-snap-align: start`.
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- Hide scrollbars using `scrollbar-width: none` and styling the pseudo-element `::-webkit-scrollbar` to `display: none`.
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- Use `Element.scrollTo()` to define a `scrollToElement` function, that scrolls the gallery to the given item.
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- Use `Array.prototype.map()` and `Array.prototype.join()` to populate the `.thumbnails` element. Give each thumbnail a `data-id` attribute with the index of the image.
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- Use `Document.querySelectorAll()` to get all the thumbnail elements. Use `Array.prototype.forEach()` to register a handler for the `'click'` event on each thumbnail, using `EventTarget.addEventListener()` and the `scrollToElement` function.
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- Use `Document.querySelector()` and `EventTarget.addEventListener()` to register a handler for the `'scroll'` event. Update the `.thumbnails` element to match the current scroll position, using the `highlightThumbnail` function.
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```html
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<div class="gallery-container">
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<div class="thumbnails"></div>
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<div class="slides">
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<div><img src="https://picsum.photos/id/1067/540/720"></div>
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<div><img src="https://picsum.photos/id/122/540/720"></div>
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<div><img src="https://picsum.photos/id/188/540/720"></div>
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<div><img src="https://picsum.photos/id/249/540/720"></div>
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<div><img src="https://picsum.photos/id/257/540/720"></div>
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<div><img src="https://picsum.photos/id/259/540/720"></div>
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<div><img src="https://picsum.photos/id/283/540/720"></div>
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<div><img src="https://picsum.photos/id/288/540/720"></div>
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<div><img src="https://picsum.photos/id/299/540/720"></div>
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</div>
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</div>
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```
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```css
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.gallery-container {
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position: relative;
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display: flex;
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justify-content: center;
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}
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.thumbnails {
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position: absolute;
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bottom: 8px;
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display: flex;
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flex-direction: row;
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gap: 6px;
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}
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.thumbnails div {
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width: 8px;
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height: 8px;
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cursor: pointer;
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background: #aaa;
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border-radius: 100%;
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}
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.thumbnails div.highlighted {
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background-color: #777;
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}
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.slides {
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margin: 0 16px;
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display: grid;
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grid-auto-flow: column;
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gap: 1rem;
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width: 540px;
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padding: 0 0.25rem;
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height: 720px;
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overflow-y: auto;
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overscroll-behavior-x: contain;
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scroll-snap-type: x mandatory;
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scrollbar-width: none;
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}
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.slides > div {
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scroll-snap-align: start;
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}
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.slides img {
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width: 540px;
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object-fit: contain;
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}
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.slides::-webkit-scrollbar {
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display: none;
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}
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```
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```js
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const slideGallery = document.querySelector('.slides');
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const slides = slideGallery.querySelectorAll('div');
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const thumbnailContainer = document.querySelector('.thumbnails');
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const slideCount = slides.length;
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const slideWidth = 540;
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const highlightThumbnail = () => {
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thumbnailContainer
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.querySelectorAll('div.highlighted')
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.forEach(el => el.classList.remove('highlighted'));
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const index = Math.floor(slideGallery.scrollLeft / slideWidth);
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thumbnailContainer
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.querySelector(`div[data-id="${index}"]`)
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.classList.add('highlighted');
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};
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const scrollToElement = el => {
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const index = parseInt(el.dataset.id, 10);
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slideGallery.scrollTo(index * slideWidth, 0);
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};
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thumbnailContainer.innerHTML += [...slides]
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.map((slide, i) => `<div data-id="${i}"></div>`)
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.join('');
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thumbnailContainer.querySelectorAll('div').forEach(el => {
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el.addEventListener('click', () => scrollToElement(el));
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});
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slideGallery.addEventListener('scroll', e => highlightThumbnail());
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highlightThumbnail();
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```
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