[rollup-plugin-html] Expose html-minifier-terser options

[JulianCataldo]

Hello,

I'm willing to open a PR for allowing finer control over HTML minification with @web/rollup-plugin-html.

Primary motivation for this feature, in my case, is preserving <!--lit-part EeTSS7FUtCM=--> comments in Declarative Shadow DOM (from Lit SSR output), thanks to the ignoreCustomComments matcher option.

But I'm sure some other peeps will find benefits by exposing the minifier API, versus a simple ON/OFF toggle.

---

Change:

if (pluginOptions.minify) {
  outputHtml = await minifyHTMLFunc(
    outputHtml,
    pluginOptions.minifyOptions
      ? pluginOptions.minifyOptions
      : {
          collapseWhitespace: true,
          removeComments: true,
          removeRedundantAttributes: true,
          removeScriptTypeAttributes: true,
          removeStyleLinkTypeAttributes: true,
          useShortDoctype: true,
          minifyCSS: true,
          minifyJS: true,
         // Or maybe with a spread here? Like `...pluginOptions.minifyOptions`
        },
  );
}

in:

web/packages/rollup-plugin-html/src/output/getOutputHTML.ts

Lines 96 to 107 in efd8579

	if (pluginOptions.minify) {
	outputHtml = await minifyHTMLFunc(outputHtml, {
	collapseWhitespace: true,
	removeComments: true,
	removeRedundantAttributes: true,
	removeScriptTypeAttributes: true,
	removeStyleLinkTypeAttributes: true,
	useShortDoctype: true,
	minifyCSS: true,
	minifyJS: true,
	});
	}

Change:

import type { Options as HTMLMinifierOptions } from 'html-minifier-terser';


  /** Whether to minify the output HTML. */
  minify?: boolean;
  /** Minification options for HTML Minifier. */
  minifyOptions?: HTMLMinifierOptions;

Association types from @types/html-minifier-terser.

in:

web/packages/rollup-plugin-html/src/RollupPluginHTMLOptions.ts

Lines 13 to 48 in efd8579

	export interface RollupPluginHTMLOptions {
	/** HTML file(s) to use as input. If not set, uses rollup input option. */
	input?: string | InputHTMLOptions | (string | InputHTMLOptions)[];
	/** HTML file glob pattern or patterns to ignore */
	exclude?: string | string[];
	/** Whether to minify the output HTML. */
	minify?: boolean;
	/** Whether to preserve or flatten the directory structure of the HTML file. */
	flattenOutput?: boolean;
	/** Directory to resolve absolute paths relative to, and to use as base for non-flatted filename output. */
	rootDir?: string;
	/** Path to load modules and assets from at runtime. */
	publicPath?: string;
	/** Transform asset source before output. */
	transformAsset?: TransformAssetFunction | TransformAssetFunction[];
	/** Transform HTML file before output. */
	transformHtml?: TransformHtmlFunction | TransformHtmlFunction[];
	/** Whether to extract and bundle assets referenced in HTML. Defaults to true. */
	extractAssets?: boolean;
	/** Whether to ignore assets referenced in HTML and CSS with glob patterns. */
	externalAssets?: string | string[];
	/** Define a full absolute url to your site (e.g. https://domain.com) */
	absoluteBaseUrl?: string;
	/** Whether to set full absolute urls for ['meta[property=og:image]', 'link[rel=canonical]', 'meta[property=og:url]'] or not. Requires a absoluteBaseUrl to be set. Default to true. */
	absoluteSocialMediaUrls?: boolean;
	/** Should a service worker registration script be injected. Defaults to false. */
	injectServiceWorker?: boolean;
	/** File system path to the generated service worker file */
	serviceWorkerPath?: string;
	/** Prefix to strip from absolute paths when resolving assets and scripts, for example when using a base path that does not exist on disk. */
	absolutePathPrefix?: string;
	/** When set to true, will insert meta tags for CSP and add script-src values for inline scripts by sha256-hashing the contents */
	strictCSPInlineScripts?: boolean;
	/** Bundle assets reference from CSS via `url` */
	bundleAssetsFromCss?: boolean;
	}

---

What do you think?

Thank you.

[bashmish]

I'd rather expose a way to override the minify function with a simple interface, seems like it fits well with the current design of the plugin. Can even be the same option set to a callback instead of a boolean:

pluginOptions.minify = (html) => {
  const minifiedHtml = /* process html */
  return minifiedHtml;
}