Rollup Smart Asset Plugin

Overview

Rollup plugin to rebase, inline or copy assets referenced from the JavaScript code.

Usage

import smartAsset from "rollup-plugin-smart-asset"

const smartAssetOpts = { ... }

export default {
  input: "src/index.tsx",
  output: {
    file: "dist/index.js",
    format: "iife"
  },
  plugins: [
    ...
    smartAsset(smartAssetOpts)
    ...
  ]
}

Configuration

For libraries it is recommended to use inline or copy mode with keepImport option to delegate bundling to consumer's package bundler. Asset hashing is not needed for this case and it is safe to set useHash: false and keepName: true.

For applications it is also recommended to use inline or copy mode with enabled by default hashing.

Default settings are set to be the same as in postcss-smart-asset to have one config for both of them.

Main options:

• url: Mode: rebase (default), inline and copy
• extensions: What file extensions to process, defaults to [".svg", ".gif", ".png", ".jpg"] unless exclude or include are used. This option is ignored if include or exclude options are used.
• include: Micromatch pattern or array of micromatch patterns for files that need to be processed by this plugin.
• exclude: Micromatch pattern or array of micromatch patterns for files that NOT need to be processed by this plugin.
• emitFiles: Disable generating files if false, by default it's true - useful when generating bundle for SSR.

For more details about include / exclude syntax please refer to: https://github.com/micromatch/micromatch

Mode: rebase

Rebase asset references to be relative to specific directory.

Output:

// without keepImport (inside wrapper)
export default "public_path_to_asset"

// with keepImport and cjs module format
const myAsset = require("relative_path_to_asset_from_bundle")

// with keepImport and esm module format
import myAsset from "relative_path_to_asset_from_bundle"

Options:

• publicPath: Reference file from JS using this path, relative to html page where asset is referenced. Could be relative, absolute or CDN.
• rebasePath: Rebase all asset urls to this directory, defaults to current directory.
• keepImport: Keep import, so consumer of your package could define their own bundle configuration.
• sourceMap: Set to true to keep source map.

Mode: inline

Inline assets as base64 urls directly in source code.

Keep in mind, all options for copy mode will be used if falled back to copy mode.

Output:

export default "data:{mimeType};base64,{data}"

Options:

• maxSize: Max file size to inline (in kb), fallback is copy mode, defaults to 14 kbytes.

Mode: copy

Copy asset to target directory and rebase original references to point to target path depending on provided configuration.

Output:

// without keepImport (inside wrapper)
export default "public_path_to_asset"

// with keepImport and cjs module format
const myAsset = require("relative_path_to_asset_from_bundle")
// + file is copied to target directory

// with keepImport and esm module format
import myAsset from "relative_path_to_asset_from_bundle"
// + file is copied to target directory

Options:

• publicPath: Reference file from JS using this path, relative to html page where asset is referenced. Could be relative, absolute or CDN.
• assetsPath: Copy assets to this directory, relative to rollup output.
• useHash: Enable to use [hash][ext] instead of default [name][ext].
• keepName: Use both hash and name [name]~[hash][ext] if useHash is true.
• nameFormat: Use custom name format using these patterns [name], [ext], [hash].
• hashOptions: Hash options.
  • hash: Any valid Node's crypto hashing algorithm e.g. sha1, md5 etc, Hash-like class (see: https://nodejs.org/api/crypto.html#crypto_class_hash), metrohash64 or metrohash128 if metrohash is installed, xxhash32 or xxhash64 if xxhash is installed. Default is sha1.
  • encoding: Hash encoding hex, base64 base62, base58, base52, base49, base36, base32, base26. Default is base52.
  • maxLength: Maximum length of returned digest. Keep in mind that reducing it increases collison probability. Default is 8.
• keepImport: Keep import, so consumer of your package could define their own bundle configuration.

Preserve Modules

Rollup preserveModules: true is supported but additional context is required for the plugin to properly detect rebased path to the asset.

Additional options needed:

• outputDir: Path to output dir, should be the same as output.dir, can't be automatically detected and neeed to be explicitly passed.
• (optional) preserveModules: Set to true to activate mode, can be automatically detected.
• (optional) inputFile: Path to main entry, should be the same as input.file, can be automatically detected. Object and array values for input.file are not supported.

Migration

Migration from v1.x to v2.x

Changes:

• Option hashOptions.hash defaults to sha1 instead of metrohash128.
• Removed dependencies: asset-hash.
• These dependencies are now optional: xxhash and metrohash.

The default configuration is changed in favor of default hash functions that are available in NodeJS without requirement to build any native extensions during npm install.

If you would like to use ultra fast metrohash64 or metrohash128 hashes then do npm install metrohash and set hashOptions.hash to metrohash64 or metrohash128.

If you would like to use ultra fast xxhash32 or xxhash64 hashes then do npm install xxhash and set hashOptions.hash to xxhash32 or xxhash64.

Alternatives

@rollup/plugin-url (ex rollup-plugin-url)

https://github.com/rollup/rollup-plugin-url or https://github.com/rollup/plugins/tree/master/packages/url

This Rollup plugin has fewer options, doesn't work if asset is already loaded by another plugin (by sourcemaps, for example) and doesn't have keepImport like option (designed for applications).

postcss-smart-asset

https://github.com/sebastian-software/postcss-smart-asset

This PostCSS plugin works for assets referenced from CSS, but doesn't work for assets imported from JavaScript.

rollup-plugin-rebase

https://github.com/sebastian-software/rollup-plugin-rebase

This Rollup plugin is designed for libraries, has keepImport like option enabled by default so can't be used for applications.

Contribution

PRs are very welcome!

License

MIT