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Image.svelte	Image.svelte
README.md	README.md
utils.ts	utils.ts

Progressive responsive image

<Image> and <NakedImage /> are Svelte component specially designed to work seamlessly with DatoCMS’s responsiveImage GraphQL query which optimizes image loading for your websites.

TypeScript ready;
Usable both client and server side;
Compatible with vanilla Svelte and Sveltekit;

Out-of-the-box features

Offers optimized version of images for browsers that support WebP/AVIF format
Generates multiple smaller images so smartphones and tablets don’t download desktop-sized images
Efficiently lazy loads images to speed initial page load and save bandwidth
Holds the image position so your page doesn’t jump while images load
Uses either blur-up or background color techniques to show a preview of the image while it loads

Setup
Usage
<Image /> vs <NakedImage />
Example
The ResponsiveImage object
<NakedImage />
- Props
- Events
<Image />

Setup

You can import the components like this:

import { Image, NakedImage } from '@datocms/svelte';

Usage

Use <Image> or <NakedImage /> in place of the regular <img /> tag
Write a GraphQL query to your DatoCMS project using the responsiveImage query

The GraphQL query returns multiple thumbnails with optimized compression. The components automatically set up the "blur-up" effect as well as lazy loading of images further down the screen.

`<Image />` vs `<NakedImage />`

Even though their purpose is the same, there are some significant differences between these two components. Depending on your specific needs, you can choose to use one or the other:

<NakedImage /> generates minimum JS footprint, outputs a single <picture /> element and implements lazy-loading using the native loading="lazy" attribute. The placeholder is set as the background to the image itself.
<Image /> has the ability to set a cross-fade effect between the placeholder and the original image, but at the cost of generating more complex HTML output composed of multiple elements around the main <picture /> element. It also implements lazy-loading through IntersectionObserver, which allows customization of the thresholds at which lazy loading occurs.

Example

For a fully working example take a look at routes directory.

Here is a minimal starting point:

<script>

import { onMount } from 'svelte';

import { Image, NakedImage } from '@datocms/svelte';

const query = gql`
  query {
    blogPost {
      title
      cover {
        responsiveImage(
          imgixParams: { fit: crop, w: 300, h: 300, auto: format }
        ) {
          # always required
          src
          width
          height
          # not required, but strongly suggested!
          alt
          title
          # blur-up placeholder, JPEG format, base64-encoded, or...
          base64
          # background color placeholder
          bgColor
          # you can omit `sizes` if you explicitly pass the `sizes` prop to the image component
          sizes
        }
      }
    }
  }
`;

export let data = null;

onMount(async () => {
  const response = await fetch('https://graphql.datocms.com/', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: "Bearer AN_API_TOKEN",
    },
    body: JSON.stringify({ query })
  })

  const json = await response.json()

  data = json.data;
});

</script>

{#if data}
	<Image data={data.blogPost.cover.responsiveImage} />
	<NakedImage data={data.blogPost.cover.responsiveImage} />
{/if}

The `ResponsiveImage` object

The data prop of both components expects an object with the same shape as the one returned by responsiveImage GraphQL call. It's up to you to make a GraphQL query that will return the properties you need for a specific use of the <datocms-image> component.

The minimum required properties for data are: src, width and height;
alt and title, while not mandatory, are all highly suggested, so remember to use them!
If you don't request srcSet, the component will auto-generate an srcset based on src + the srcSetCandidates prop (it can help reducing the GraphQL response size drammatically when many images are returned);
We strongly to suggest to always specify { auto: format } in your imgixParams, instead of requesting webpSrcSet, so that you can also take advantage of more performant optimizations (AVIF), without increasing GraphQL response size;
If you request both the bgColor and base64 property, the latter will take precedence, so just avoid querying both fields at the same time, as it will only make the GraphQL response bigger 😉;
You can avoid requesting sizes and directly pass a sizes prop to the component to reduce the GraphQL response size;

Here's a complete recap of what responsiveImage offers:

property	type	required	description
src	string	✅	The `src` attribute for the image
width	integer	✅	The width of the image
height	integer	✅	The height of the image
alt	string	❌	Alternate text (`alt`) for the image (not required, but strongly suggested!)
title	string	❌	Title attribute (`title`) for the image (not required, but strongly suggested!)
sizes	string	❌	The HTML5 `sizes` attribute for the image (omit it if you're already passing a `sizes` prop to the Image component)
base64	string	❌	A base64-encoded thumbnail to offer during image loading
bgColor	string	❌	The background color for the image placeholder (omit it if you're already requesting `base64`)
srcSet	string	❌	The HTML5 `srcSet` attribute for the image (can be omitted, the Image component knows how to build it based on `src`)
webpSrcSet	string	❌	The HTML5 `srcSet` attribute for the image in WebP format (deprecated, it's better to use the `auto=format` Imgix transform instead)
aspectRatio	float	❌	The aspect ratio (width/height) of the image

`<NakedImage />`

Props

prop	type	default	required	description
data	`ResponsiveImage` object		✅	The actual response you get from a DatoCMS `responsiveImage` GraphQL query ****
pictureClass	string	null	❌	Additional CSS class for the root `<picture>` tag
pictureStyle	CSS properties	null	❌	Additional CSS rules to add to the root `<picture>` tag
imgClass	string	null	❌	Additional CSS class for the `<img>` tag
imgCtyle	CSS properties	null	❌	Additional CSS rules to add to the `<img>` tag
priority	Boolean	false	❌	Disables lazy loading, and sets the image fetchPriority to "high"
sizes	string	undefined	❌	The HTML5 `sizes` attribute for the image (will be used `data.sizes` as a fallback)
usePlaceholder	Boolean	true	❌	Whether the image should use a blurred image placeholder
srcSetCandidates	Array	[0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4]	❌	If `data` does not contain `srcSet`, the candidates for the `srcset` attribute of the image will be auto-generated based on these width multipliers

Events

prop	description
@load	Emitted when the image has finished loading

`<Image />`

Props

prop	type	default	required	description
data	`ResponsiveImage` object		✅	The actual response you get from a DatoCMS `responsiveImage` GraphQL query.
class	string	null	❌	Additional CSS class of root node
style	string	null	❌	Additional CSS rules to add to the root node
pictureClass	string	null	❌	Additional CSS class for the inner `<picture />` tag
pictureStyle	string	null	❌	Additional CSS rules to add to the inner `<picture />` tag
imgClass	string	null	❌	Additional CSS class for the image inside the `<picture />` tag
imgStyle	string	null	❌	Additional CSS rules to add to the image inside the `<picture />` tag
layout	'intrinsic' \| 'fixed' \| 'responsive' \| 'fill'	"intrinsic"	❌	The layout behavior of the image as the viewport changes size
fadeInDuration	integer	500	❌	Duration (in ms) of the fade-in transition effect upoad image loading
intersectionThreshold	float	0	❌	Indicate at what percentage of the placeholder visibility the loading of the image should be triggered. A value of 0 means that as soon as even one pixel is visible, the callback will be run. A value of 1.0 means that the threshold isn't considered passed until every pixel is visible.
intersectionMargin	string	"0px 0px 0px 0px"	❌	Margin around the placeholder. Can have values similar to the CSS margin property (top, right, bottom, left). The values can be percentages. This set of values serves to grow or shrink each side of the placeholder element's bounding box before computing intersections.
lazyLoad	Boolean	true	❌	Wheter enable lazy loading or not
explicitWidth	Boolean	false	❌	Wheter the image wrapper should explicitely declare the width of the image or keep it fluid
objectFit	String	null	❌	Defines how the image will fit into its parent container when using layout="fill"
objectPosition	String	null	❌	Defines how the image is positioned within its parent element when using layout="fill".
priority	Boolean	false	❌	Disables lazy loading, and sets the image fetchPriority to "high"
srcSetCandidates	Array	[0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4]	❌	If `data` does not contain `srcSet`, the candidates for the `srcset` attribute of the image will be auto-generated based on these width multipliers
sizes	string	undefined	❌	The HTML5 `sizes` attribute for the image (will be used `data.sizes` as a fallback)
onLoad	() => void	undefined	❌	Function triggered when the image has finished loading
usePlaceholder	Boolean	true	❌	Whether the component should use a blurred image placeholder

Events

prop	description
@load	Emitted when the image has finished loading

Layout mode

With the layout property, you can configure the behavior of the image as the viewport changes size:

When intrinsic, the image will scale the dimensions down for smaller viewports, but maintain the original dimensions for larger viewports.
When fixed, the image dimensions will not change as the viewport changes (no responsiveness) similar to the native img element.
When responsive (default behaviour), the image will scale the dimensions down for smaller viewports and scale up for larger viewports.
When fill, the image will stretch both width and height to the dimensions of the parent element, provided the parent element is relative.
- This is usually paired with the objectFit and objectPosition properties.
- Ensure the parent element has position: relative in their stylesheet.

Intersection Observer

IntersectionObserver is the API used to determine if the image is inside the viewport or not. Browser support is really good: with Safari adding support in 12.1, all major browsers now support IntersectionObserver natively.

If IntersectionObserver object is not available, the component treats the image as it's always visible in the viewport. Feel free to add a polyfill so that it will also 100% work on older versions of iOS and IE11.

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README.md

Progressive responsive image

Out-of-the-box features

Table of contents

Setup

Usage

`<Image />` vs `<NakedImage />`

Example

The `ResponsiveImage` object

`<NakedImage />`

Props

Events

`<Image />`

Props

Events

Layout mode

Intersection Observer

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parent directory

README.md

Progressive responsive image

Out-of-the-box features

Table of contents

Setup

Usage

<Image /> vs <NakedImage />

Example

The ResponsiveImage object

<NakedImage />

Props

Events

<Image />

Props

Events

Layout mode

Intersection Observer

`<Image />` vs `<NakedImage />`

The `ResponsiveImage` object

`<NakedImage />`

`<Image />`