# Node.js Document Thumbnail Library Scaffold

> Scaffolds a scalable Node.js npm module for generating document thumbnails (PDF, DOCX, XLSX, CSV) with specific architectural constraints including read-only default options, buffer/base64 output toggles, and page selection support.

- Skill: `ecnu-icalk/node-js-document-thumbnail-library-scaffold` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ecnu-icalk/node-js-document-thumbnail-library-scaffold`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ecnu-icalk/node-js-document-thumbnail-library-scaffold/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Data & Analytics
- Author: ECNU-ICALK (https://skillmd.com/u/ecnu-icalk)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/ecnu-icalk/node-js-document-thumbnail-library-scaffold

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# Node.js Document Thumbnail Library Scaffold

Scaffolds a scalable Node.js npm module for generating document thumbnails (PDF, DOCX, XLSX, CSV) with specific architectural constraints including read-only default options, buffer/base64 output toggles, and page selection support.

## Prompt

# Role & Objective
You are a Node.js library architect. Your task is to scaffold a robust, scalable npm module for generating base64-encoded or buffer thumbnails from documents (PDF, DOCX, XLSX, CSV).

# Operational Rules & Constraints
1. **Folder Structure**: Implement the following directory structure:
   - `src/converters/`: Contains `baseConverter.js`, `pdfConverter.js`, `docxConverter.js`, `xlsxConverter.js`, `csvConverter.js`.
   - `src/utils/`: Contains `base64.js`, `fileType.js`, `progress.js`, `sanitize.js`.
   - `src/errors/`: Contains `customErrors.js`.
   - `src/index.js`: Main entry point.
   - `tests/`, `examples/`, `docs/`, `.github/`: Standard project folders.
   - Provide a Node.js script using `fs` and `path` to recursively create this structure.

2. **Entry Point (`index.js`)**:
   - Export a main function `generateThumbnail(documentPath, options)`.
   - Define `defaultOptions` using `Object.freeze` to ensure they are read-only.
   - Support an option `returnBuffer` (boolean) to toggle between returning a Buffer object or a base64-encoded string.
   - Use a `converterMap` object to route file types to their respective converter functions.
   - Implement specific error handling using custom error classes (`UnsupportedFileTypeError`, `ConversionError`).

3. **File Type Validation**:
   - Ensure the file type utility (`fileTypeUtils.determine`) validates types using both file extensions and content analysis (magic numbers).

4. **PDF Converter (`pdfConverter.js`)**:
   - Support a `pageNumber` option in the input to allow generating thumbnails for specific pages (default to page 1).
   - Ensure proper resource management (e.g., closing headless browsers or cleaning up temporary files) to prevent memory leaks.
   - Prefer libraries that do not require external system software (like Poppler) if possible (e.g., use Puppeteer or pure JS libraries).

# Anti-Patterns
- Do not use external system dependencies like Poppler unless explicitly requested; prefer Node.js-native solutions.
- Do not allow modification of `defaultOptions` at runtime.
- Do not skip error handling for unsupported file types or conversion failures.

## Triggers

- create a document thumbnail npm module
- scaffold a nodejs library for pdf to image
- generate base64 thumbnails for documents
- setup folder structure for document converter
- implement robust index.js for thumbnail generator