coding-horror/basic-computer-games · warning · Error

Game "${folder}" is missing a javascript folder

Error message

Game "${folder}" is missing a javascript folder

What it means

Thrown by findJSFilesInFolder() when a game directory lacks a child folder named 'javascript' (the JAVASCRIPT_FOLDER constant). The index builder expects every non-ignored game folder to contain a 'javascript/' subfolder holding the web port. This throw is caught by the try/catch in main() at build-index.js:134-139, so it surfaces as a console warning and the game is simply omitted from index.html rather than crashing the build.

Source

Thrown at 00_Utilities/build-index.js:93

				</main>
			</article>
		</body>
	`;

	return `
		<!DOCTYPE html>
		<html lang="en">
		${head}
		${body}
		</html>
	`.trim().replace(/\s\s+/g, '');
}

function findJSFilesInFolder(folder) {
	// filter folders that do not include a subfolder called "javascript"
	const hasJavascript = fs.existsSync(`${folder}/${JAVASCRIPT_FOLDER}`);
	if (!hasJavascript) {
		throw new Error(`Game "${folder}" is missing a javascript folder`);
	}

	// get all files in the javascript folder
	const files = fs.readdirSync(`${folder}/${JAVASCRIPT_FOLDER}`);

	// filter files only allow .html files
	const htmlFiles = files.filter(file => file.endsWith('.html'));
	const mjsFiles = files.filter(file => file.endsWith('.mjs'));
	const entries = [
		...htmlFiles,
		...mjsFiles
	].filter(file => !IGNORE_FILES.includes(file));

	if (entries.length == 0) {
		throw new Error(`Game "${folder}" is missing a HTML or node.js file in the folder "${folder}/${JAVASCRIPT_FOLDER}"`);
	}

	return entries.map(file => path.join(folder, JAVASCRIPT_FOLDER, file));

View on GitHub (pinned to 5301155192)

Solutions

  1. Confirm the game has a javascript port; if not, this is expected behavior and the warning can be ignored.
  2. If it should be skipped silently, add the folder prefix to IGNORE_FOLDERS_START_WITH at build-index.js:16.
  3. Create the missing 'javascript' subfolder with at least one .html or .mjs file.
Defensive patterns

Strategy: try-catch

Validate before calling

// Check before calling findJSFilesInFolder
const fs = require('fs');
function hasJSFolder(folder) {
  return fs.existsSync(`${folder}/javascript`);
}
// skip folders without a javascript port instead of throwing

Try / catch

// Already implemented in main() (build-index.js:134-139):
try { files = findJSFilesInFolder(folder); }
catch (error) { console.warn(`Game "${name}" is missing a javascript implementation: ${error.message}`); return null; }

Prevention

When it happens

Trigger: Running `node ./00_Utilities/build-index.js` when a numbered game folder (e.g. '03_Animal') exists without a 'javascript' subfolder; main() calls findJSFilesInFolder for that folder and fs.existsSync returns false at line 91.

Common situations: A game has only a Java/Python/C# port and no JavaScript port yet; a folder was renamed/moved leaving an empty stub; a new game folder was added before its javascript/ implementation.

Related errors

AI-assisted analysis of coding-horror/basic-computer-games@5301155192 (2026-08-13). Data as JSON: /api/errors/160d62a9b063597c. Report an issue: GitHub.