Integrations

unlazy supports lazy loading images in your framework of choice. Each package provides a UnLazyImage component as a drop-in replacement for the native <img> element.

Generic How-To

To create a component for the framework of your choice, keep the following in mind:

1. The component should wrap a native <img> element with the loading="lazy" attribute set.
2. The component should support at least a src or srcset attribute.
3. Import the lazyLoad function from the unlazy library and call it with a HTMLImageElement or HTMLSourceElement as the first argument:

import { lazyLoad } from 'unlazy'

lazyLoad(target)

4. If the component gets unmounted before the image is loaded, call the cleanup function returned by lazyLoad. Take the following example from the Vue integration:

import { lazyLoad } from 'unlazy'

const target = ref<HTMLImageElement | undefined>()

onMounted(() => {
  if (target.value) {
    const cleanup = lazyLoad(target.value)
    onBeforeUnmount(cleanup)
  }
})

That's it!

Server-Side Rendering

unlazy supports server-side rendering for BlurHash and ThumbHash strings. This means that you can generate the placeholder images for the src attribute with SSR and avoid the Cumulative Layout Shift (CLS) caused by the images loading after the page has been rendered.

Both the unlazy/blurhash and unlazy/thumbhash exports provide a createPngDataUri function that can be used to generate a PNG data URI for a BlurHash or ThumbHash string, respectively. This function can be used to generate the src attribute for the <img> element.

• BlurHash createPngDataUri – Generate a PNG data URI for a BlurHash string
• ThumbHash createPngDataUri – Generate a PNG data URI for a ThumbHash string

TIP

The Nuxt integration uses this approach to enable the UnLazyImage component to provide an SSR src attribute for the initial render.

Available Integrations

The following integrations are available as of now:

Frontend Frameworks

• Vue
• React
• Solid
• Svelte

Meta-Frameworks

TIP

These include SSR-decoding of BlurHash and ThumbHash strings.

• Nuxt