The HTML compression postbuild file for compressing the HTML to Brotli 11. (contains logging for Cloudflare pages builds)

html-compression.js

import fs from 'fs';
import path from 'path';

import { brotliCompress, BROTLI_LEVEL } from './compression.js';

/**
 * Recursively find all .html files in a directory.
 * @param {string} dir - Directory to search
 * @param {string[]} [acc=[]] - Accumulator for results
 * @returns {string[]} Relative paths to .html files
 */
function findHtmlFiles(dir, acc = []) {
	const entries = fs.readdirSync(dir, { withFileTypes: true });
	for (const entry of entries) {
		const fullPath = path.join(dir, entry.name);
		const relPath = path.relative('./_site', fullPath);
		if (entry.isDirectory()) {
			findHtmlFiles(fullPath, acc);
		} else if (entry.isFile() && entry.name.endsWith('.html')) {
			acc.push(relPath);
		}
	}
	return acc;
}

/**
 * Compress all HTML files in _site with Brotli level 11, writing .br files.
 * Call after Eleventy build when HTML has been output.
 *
 * Serving: functions/[[path]].js performs content negotiation for HTML document requests.
 * When client sends Accept-Encoding: br, it serves the .br file with Content-Encoding: br.
 * Otherwise it passes through to static assets (uncompressed HTML).
 */
export function compressHtmlFiles() {
	const startTime = Date.now();
	console.log('\n━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━');
	console.log('🚀 PRODUCTION POSTBUILD: Starting HTML Brotli compression');
	console.log('━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n');

	const siteDir = path.join('./_site');
	if (!fs.existsSync(siteDir)) {
		console.log('⚠️  _site directory not found, skipping HTML compression');
		return;
	}

	const htmlFiles = findHtmlFiles(siteDir);
	if (htmlFiles.length === 0) {
		console.log('⚠️  No HTML files found, skipping compression');
		return;
	}

	let compressedCount = 0;
	let skippedCount = 0;
	let totalOriginal = 0;
	let totalCompressed = 0;
	const errors = [];

	for (const relPath of htmlFiles) {
		const inputPath = path.join(siteDir, relPath);
		const outputPath = `${inputPath}.br`;

		try {
			if (fs.existsSync(outputPath)) {
				const inputStats = fs.statSync(inputPath);
				const outputStats = fs.statSync(outputPath);
				if (outputStats.mtime >= inputStats.mtime) {
					skippedCount++;
					continue;
				}
			}

			const fileContent = fs.readFileSync(inputPath);
			const originalSize = fileContent.length;

			const brotliBuffer = brotliCompress(fileContent, BROTLI_LEVEL);
			const compressedSize = brotliBuffer.length;

			fs.writeFileSync(outputPath, brotliBuffer);
			compressedCount++;
			totalOriginal += originalSize;
			totalCompressed += compressedSize;
		} catch (error) {
			errors.push(`❌ ${relPath}: ${error.message}`);
		}
	}

	const totalTime = Date.now() - startTime;
	const savedPercent = totalOriginal > 0 ? ((1 - totalCompressed / totalOriginal) * 100).toFixed(1) : '0';

	console.log(`✅ Compressed ${compressedCount} HTML file(s) (${skippedCount} skipped, up-to-date)`);
	if (compressedCount > 0) {
		console.log(
			`   ${(totalOriginal / 1024).toFixed(1)} KB → ${(totalCompressed / 1024).toFixed(1)} KB (${savedPercent}% smaller)`
		);
	}
	console.log(`   Finished in ${totalTime}ms (${(totalTime / 1000).toFixed(2)}s)`);

	if (errors.length > 0) {
		console.error('\nErrors:');
		errors.forEach(e => console.error(`  ${e}`));
	}

	console.log('\n━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n');
}