HazeHash Nuxt

Nuxt module for HazeHash placeholders: it registers the PlaceholderImage component and generates the hashes of your images during the build, so the component works with just a src. On the server the markup contains only the average colour and the aspect ratio; in the browser the blurred preview is drawn into a canvas and the real image fades in over it.

Part of the hazehash monorepo. Core package and Vue wrapper: hazehash, hazehash-vue.

Features

• Hashes generated during the build — the module scans the configured folders and encodes every image once, with no command to run
• A component that needs only a src — <PlaceholderImage> looks the hash up by the image URL; a hash passed explicitly always wins, which is the way to use hashes stored in a database or a CMS
• A cache by file size and modification time — results are kept in node_modules/.cache/hazehash/manifest.json together with the budget and the profile, so unchanged images are not encoded again
• Regenerated while you develop — when an image in a scanned folder is added, changed or removed, the manifest is rebuilt
• A failure never breaks the build — a missing sharp disables generation with one warning, and an image that cannot be decoded is skipped with a warning
• Auto-imports — useHazeHash(src) and usePlaceholder() are available without an import
• Hydration cannot mismatch — the server renders only the average colour and the aspect ratio, and the canvas is added after mount

When you'd reach for this

You are on Nuxt, your images live in the project, and you want a blurred placeholder for each of them without maintaining a list of hashes.

• A site with a public folder full of photos — Add the module, and every image there gets its hash during the build, with no script and no manual step.
• A project that rebuilds often — The cache by file size and modification time means only new and changed images are encoded again.
• A mix of local images and hashes from a database — Local images take the generated hash by src, and records from a database pass their own hash.

Installation

npm install hazehash-nuxt
npm install --save-dev sharp

// nuxt.config.ts
export default defineNuxtConfig({
  modules: ['hazehash-nuxt'],
});

Requires Nuxt ^3.9.0 and Node.js 20+. sharp is needed in your project for the build-time generation; without it the module prints a warning and the component works only with an explicit hash.

Quick start

<template>
  <PlaceholderImage src="/images/hero.jpg" alt="Hero" :width="1600" :height="900" />
</template>

More examples

How it works

1. At build time the module scans the configured directories and encodes every image with hazehash/node. Results are cached per file (size and mtime) in node_modules/.cache/hazehash/manifest.json, so unchanged images are not encoded again.
2. The manifest { "/images/hero.jpg": "Ed7UwRWKKv5znm6a7sC1tziHDNpMuCikxrYpIg" } is exposed as the virtual module #hazehash/manifest.
3. The component looks up hash by src when no hash prop is given. A hash passed explicitly always wins.
4. In development the manifest is regenerated when an image in a scanned directory changes.

If sharp is missing or an image cannot be decoded, the build continues and a warning is printed.

Options

export default defineNuxtConfig({
  modules: ['hazehash-nuxt'],
  hazehash: {
    componentName: 'PlaceholderImage', // name of the registered component
    generate: true, // set to false to use only explicit `hash` props
    dirs: [{ dir: 'public', prefix: '/' }], // directories and the URL prefix of their files
    extensions: ['.jpg', '.jpeg', '.png', '.webp', '.avif', '.gif'],
    budget: 28, // maximum bytes per hash
    profile: 'default', // 'fast' | 'default' | 'high'
  },
});

A file public/images/hero.jpg in the default directory gets the key /images/hero.jpg, which is the src you write in the template. A folder that your server publishes under another URL takes a prefix: { dir: 'media/photos', prefix: '/photos/' }.

Hashes stored elsewhere

hazehash: {
  generate: false,
}

<PlaceholderImage
  :src="photo.url"
  :hash="photo.hash"
  :width="photo.width"
  :height="photo.height"
  alt=""
/>

To produce those hashes, use the command that comes with hazehash: npx hazehash encode ./public/images -f json -o hashes.json.

Auto-imports

<script setup lang="ts">
const props = defineProps<{ src: string }>();
const hash = useHazeHash(() => props.src); // ComputedRef<string | undefined>
const { canvas, backgroundColor, aspectRatio } = usePlaceholder(hash);
</script>

useHazeHash(src) returns the generated hash for an image URL, or undefined. usePlaceholder(hash, { size }) comes from hazehash-vue for custom markup.

Documentation & links

• 📖 Full documentation: npm.vuecraft.ru/en/packages/hazehash
• 🌐 VueCraft: vuecraft.ru/en
• 👤 Author: macrulez.ru/en
• 💻 GitHub: macrulezru/hazehash/packages/nuxt
• 📦 NPM: hazehash-nuxt
• 🐛 Issues: github.com/macrulezru/hazehash/issues

License

MIT

💖 Support the project

Open source takes time and effort. If this library saves you time or brings value, consider supporting further development.

Thank you for being part of this journey. ❤️