sanity-image

A well-considered React component for displaying images from Sanity. At a glance:

• Outputs a single <img> tag, no nested DOM structure to mess with
• Zero styling included so you can style it however you want…it's just an img tag!
• Supports low-quality image previews out of the box, without build-time penalties (native lazy loading)
• Generates a srcSet automatically based on the width you specify
• Dynamic srcSet factor based on image output width
• Knows exactly what size the image will be and sets width and height attributes accordingly
• Supports crop and hotspot values from the Sanity Studio
• Automatically crops to the most “interesting” part of the image if the aspect ratio changes and no hotspot is provided
• Images are never scaled up
• Tiny 4kb bundle size (2kb gzipped)
• No dependencies
• TypeScript support
• Works with Gatsby, Next.js, and any other React-based framework
• Polymorphic component (supports as prop to render as a custom component)

Quick Start

Install it:

yarn add sanity-image
# or
npm install sanity-image

Use it:

You can find the full writeup on getting going below, but in the interest of making it easy to see if this is the thing you are looking for, here’s a quick example of most of what you’ll need to know:

Simplest Case:

This will render the image out assuming it will be displayed at half its original width with a srcSet included (multiplies vary based on original image size):

import { SanityImage } from "sanity-image"

const YourSweetComponent = ({ image }: ComponentProps) => (
  <SanityImage
    // Pass the Sanity Image ID (`_id`) (e.g., `image-abcde12345-1200x800-jpg`)
    id={image._id}
    baseUrl="https://cdn.sanity.io/images/abcd1234/production/"
    alt="Demo image"
  />
)

More full-featured example:

import { SanityImage } from "sanity-image"

const YourSweetComponent = ({ image }: ComponentProps) => (
  <SanityImage
    // Pass the Sanity Image ID (`_id`) (e.g., `image-abcde12345-1200x800-jpg`)
    id={image._id}
    //
    // You can set the base URL manually, or let it be constructed by passing
    // `projectId` and `dataset` props.
    baseUrl="https://cdn.sanity.io/images/abcd1234/production/"
    //
    // Specify how big it is expected to render so a reasonable srcSet can be
    // generated using `width`, `height`, or both
    width={500}
    height={250}
    //
    // Choose whether you want it to act like `object-fit: cover` or
    // `object-fit: contain`, or leave it out to use the default (contain)
    mode="cover"
    //
    // Have hotspot or crop data from Sanity? Pass it in!
    hotspot={image.hotspot}
    crop={image.crop}
    //
    // Want low-quality image previews? Fetch them from Sanity and pass them in too.
    preview={image.asset.metadata.lqip}
    //
    // Have a burning desire to have Sanity change the format or something?
    // Most of the visual effects from the Sanity Image API are available:
    queryParams={{ sharp: 30, q: 80 }}
    //
    // Anything else you want to pass through to the img tag? Go for it!
    alt="Sweet Christmas!"
    className="big-ol-image"
    sizes="(min-width: 500px) 500px, 100vw"
  />
)

export default YourSweetComponent

That’s the gist. Read on for more. 👇

Details

How it works at a glance:

• The image ID is parsed to determine the source image dimensions and format
• SVG images get special treatment from the Sanity Image API (they don't support params), so they're handled a bit differently (check SanityImage.ts for details)
• All other images have src and srcSet props generated based on the width and height props you pass in (or the image dimensions if you don't pass in a width or height)
• The srcSet widths depend on the size of the output image and the original image; there's some logic to avoid wasteful tiny images or giant jumps in size between large entries (see dynamicMultipliers in urlBuilder.ts)
• Values in the srcSet are never duplicated and never upscale the image
• Since we can compute the output dimensions of the image in all cases, the width and height attributes are set automatically to avoid layout shifts
• A few image params are applied by default:
• auto=format - Sanity will use AVIF images if they're supported by the browser (https://www.sanity.io/help/avif) (note: if you specify fm manually, this won't be set)
• fit - if the image aspect ratio isn't changed, this will be set to max; if the aspect ratio will change it's set to crop; you don't really need to worry about this though
• q - the quality is set to 75 by default, but you can override it with the queryParams prop
• The loading attribute will be set to lazy if it isn't supplied; use loading="eager" for images above the fold
• The alt attribute will be set to an empty string if it isn't supplied; set it if it isn't a decorative image!
• By default it renders an img tag (two if you pass in a preview), but you can pass in a custom component to render as using the as prop (see the SanityImage.test.tsx file for an example of this)
• If you wanna get weird you can also import the buildSrc and buildSrcSet exports to do your own thing with. You get a lot of the magic still this way with a skosh more control.
• Similarly, the parseImageId function is available as a named export; it takes an image ID and returns an object with the image id, dimensions, and format.
• Query params passed to Sanity are all sorted and minimized like heck for improved caching and smaller URLs. Pass in a height only? Don't be alarmed, but it'll be converted to a w param without altering what you're asking Sanity for. Ask for mode="cover" but the aspect ratio matches the source? It'll be ignored and fall back to fit=max with just a w param. You get the idea (I hope, or at least, I'm pretending, but no judgement if you don't, it's definitely 11:09pm and I'm on fumes)

Props

This is mostly copied and reformatted from the types.ts file; if you're comfortable with TypeScript, that might give you more detail.

• id (string) — Required - The Sanity Image ID (_id or _ref field value)
• mode ("cover" | "contain") — Optional - Use cover to crop the image to match the requested aspect ratio (based on width and height). Use contain to fit the image to the boundaries provided without altering the aspect ratio. Defaults to "contain". See the image below for a comparison.
• width (number) — Optional - The target width of the image in pixels. Only used for determining the dimensions of the generated assets, not for layout. Use CSS to specify how the browser should render the image instead.
• height (number) — Optional - The target height of the image in pixels. Only used for determining the dimensions of the generated assets, not for layout. Use CSS to specify how the browser should render the image instead.
• hotspot ({ x: number, y: number }) — Optional - The hotspot coordinates to use for the image. Note: hotspot width and height are not used.
• crop ({ top: number, bottom: number, left: number, right: number }) — Optional - The crop coordinates to use for the image.
• preview (string) — Optional - A low-quality image preview to use while the full-size image is loading. This should be a base64-encoded image string.
• as (React.ElementType) — Optional - The component to render as. Defaults to "img".
• baseUrl (string) — Optional - The base URL to use for the image. If not specified, the projectId and dataset props will be used to construct the URL.
• projectId (string) — Optional - The Sanity project ID to use for the image. Only used if baseUrl is not specified.
• dataset (string) — Optional - The Sanity dataset to use for the image. Only used if baseUrl is not specified.
• queryParams (object) — Optional - An object of query parameters to pass to the Sanity Image API. See the Sanity Image API documentation for a list of available options.

That's the gist. There's a ton more in the inline comments and types and such, and I'll add more details as I think of them. Feel free to open an issue or start a discussion if you have questions or suggestions, or find me on the Sanity Slack!

⚠️ “Help! My full-size image isn’t loading!"

SanityImage is relying on browser-native deferred image loading. This relies on the <img> element being visible on the page to trigger loading automatically. If the image is hidden or covered by another element, it may never be loaded.

For example, if you are using overflow: hidden on a parent element, the image might be positioned in a way that it is not treated as visible by the browser. This can also happen if you have display: none on the image or a parent element, or if the image is positioned off-screen (e.g., in a carousel, or waiting for an animation to reveal it).

Inspecting the DOM in your browser’s dev tools and checking the position of the <img> element with the data-loading attribute can help you identify the issue usually. Once you can identify the cause of the image being hidden, you can adjust the CSS styles on the img[data-loading] element to make it visible.

For reference, the full-size image sits immediately adjacent to the preview image and has the following default styles while loading:

position: absolute;
width: 10px !important; /* must be > 4px to be lazy loaded */
height: 10px !important; /* must be > 4px to be lazy loaded */
opacity: 0;
zindex: -10;
pointerevents: none;
userselect: none;

Tips

Choosing the right mode

If you are providing only one dimension (width or height, but not both), it doesn't matter since the behavior will be the same.

• Contain mode will treat the dimensions you provide as boundaries, resizing the image to fit inside of them. The output image will match the aspect ratio of the original image (i.e., no cropping will occur).
• Cover mode will treat the dimensions you provide as a container, resizing the image to completely fill the dimensions. The output image will match the aspect ratio of the dimensions you provide.

Here's a visual of this in action:

Wrap it internally

To improve the DX of using sanity-image, create a wrapper component in your app that sets the baseUrl prop (or projectId and dataset). This keeps the configuration in one place and gives you an entry point to add any other logic you might need. There's a full ImageWrapper example in the examples folder including comments. Here's a simplified version of that example for quick reference:

import * as React from "react"
import { SanityImage, type WrapperProps } from "sanity-image"

export const Image = <T extends React.ElementType = "img">(
  props: WrapperProps<T>
) => <SanityImage baseUrl="<your-baseurl-here>" {...props} />

👩‍🎤 Using Emotion’s jsxImportSource? Read this.

When you set the jsxImportSource to @emotion/react it replaces some core React types with those of its own. This allows Emotion’s polymorphic components to work, but it also makes typing a polymorphic component like <SanityImage> a bit harder. This is okay when it's used directly, but the wrapper approach winds up breaking it—the use of Omit to remove configuration props breaks the polymorphism and prompts TS to complain about unexpected props.

I am not a TS wizard, alas, and despite lots of reading and attempting to make something that works out of the box for Emotion, I have not managed to do so. Instead I recommend using @ts-expect-error on the <SanityImage> line in your wrapper. This will tell TS to ignore the props we're passing in, but it will still ensure your in-app <Image> component works as expected with full polymorphic type support.

export const Image = <T extends React.ElementType = "img">(
  props: WrapperProps<T>
) => (
  /* @ts-expect-error Emotion types are incompatible with polymorphic component */
  <SanityImage baseUrl="<your-baseurl-here>" {...props} />
)

Styling your images

I recommend setting something like the following CSS for images in your project, then overriding styles as needed. This will ensure images act like block-level elements with infinitely scalable contents even with the width and height attributes set. It also makes it easier to handle responsiveness—if your container gets smaller, the image gets smaller.

img {
  display: block;
  max-width: 100%;
  width: 100%;
  height: auto;
}

Here's an example of how that works when using, for example, a 3-column grid that fills the viewport until it is a maximum of 1,200px wide (plus padding). This produces columns that are 390px at most on desktop:

```jsx

{["image-a", "image-b", "image-c"].map((imageId) => (