Build Flags

unlazy uses build-time flags to enable tree-shaking of unused features, reducing bundle size. Bundlers replace these flags at build time, allowing dead code elimination for features your project doesn't use.

Common bundlers support the define option for setting build flags:

• Vite
• @rollup/plugin-replace
• esbuild

As an example, you can tree-shake the hash decoding algorithms in Vite by setting the define option in your vite.config.ts file:

// `vite.config.ts`
import { defineConfig } from 'vite'

export default defineConfig({
  define: {
    // Defaults to `true`
    __UNLAZY_HASH_DECODING__: false,
    // Defaults to `true`
    __UNLAZY_LOGGING__: false,
  },
})

Disable Hash Decoding ^0.10.0

unlazy includes BlurHash and ThumbHash decoding algorithms (from fast-blurhash and thumbhash packages). If your project doesn't use hash-based placeholders, you can exclude these dependencies entirely:

• __UNLAZY_HASH_DECODING__: Set to false to tree-shake hash decoding code. Default is true.

When disabled, the bundler removes:

• BlurHash and ThumbHash decoding libraries
• Hash-related code paths in lazyLoad()
• Associated dependencies from the final bundle

WARNING

This flag only affects the main entry point. If you directly import unlazy/blurhash or unlazy/thumbhash, those modules will still be bundled regardless of this flag.

Disable Client Logging ^0.10.2

unlazy helps you locate missing data-src or data-srcset attributes by logging warnings in the browser console. An example warning message looks like this:

[unlazy] Missing `data-src` or `data-srcset` attribute: <img>

To disable these warnings, use the following build flag:

• __UNLAZY_LOGGING__: Set to false to disable warnings. Default is true.