Vanilla Artifact Builder

Build vanilla JavaScript claude.ai artifacts using a clean workflow that keeps HTML, CSS, and JavaScript in separate files during development, then bundles them into a single HTML artifact for display. Supports round-trip unbundling to extract source files from bundled artifacts.

Workflow

1. •Initialize the project using scripts/init-vanilla-artifact.sh (creates src/ directory)
2. •Develop your artifact by editing files in the src/ directory
3. •Optionally add images to src/images/
4. •Bundle with scripts/bundle-vanilla-artifact.sh (bundles everything in src/)
5. •Display artifact to user
6. •(Optional) Extract source files using scripts/unbundle-vanilla-artifact.sh (recreates src/ directory)

Stack: Vanilla JavaScript + HTML + CSS + Parcel (bundling) + html-inline + source metadata

Key Principle: The src/ directory is the ground truth for what gets bundled. Everything in src/ (HTML, CSS, JS, and images) is included in the bundle and metadata.

Critical Best Practices

The src/ directory is the single source of truth:

All development happens in the src/ directory:

project/
├── src/              ← Everything here gets bundled
│   ├── index.html
│   ├── styles.css
│   ├── script.js
│   └── images/       ← Place images here
│       └── logo.png
├── bundle.html       ← Generated artifact
├── dist/             ← Build output (temporary)
├── node_modules/     ← Dependencies (temporary)
└── .gitignore

When sharing files with users:

✅ Share the src/ directory - Contains all editable source files

• •HTML, CSS, JS files
• •Images in images/ subdirectory
• •Works as a static website when opened locally
• •Typical size: <50KB even with small images

✅ Share bundle.html - The single-file artifact

❌ NEVER share:

• •dist/ directory (build output, not source)
• •node_modules/ directory (40MB+ of dependencies)
• •.parcel-cache/ directory
• •package.json or build configuration files
• •Compressed archives of the entire project directory

Simple rule: Share only what's in src/ plus the bundle.html artifact. Everything else is temporary build infrastructure.

When to Use This Skill

Use this skill when:

• •User wants separate HTML, CSS, and JS files for better code organization
• •Creating interactive vanilla JavaScript artifacts
• •Building artifacts that would benefit from modular file structure
• •User wants to extract/edit source files from a bundled artifact

Do NOT use this skill when:

• •User requests a simple single-file HTML artifact (create directly instead)
• •User requests React/TypeScript artifacts (use artifacts-builder skill instead)
• •Artifact is trivial and doesn't benefit from separate files

Quick Start

Step 1: Initialize Project

Run the initialization script to create a new vanilla JS project:

bash scripts/init-vanilla-artifact.sh <project-name>
cd <project-name>

This creates a project with clear separation between source and build:

project-name/
├── src/                    ← All source files (ground truth)
│   ├── index.html
│   ├── styles.css
│   ├── script.js
│   └── images/             ← Place image files here
│       └── README.md
└── .gitignore

After building, additional files appear:

project-name/
├── src/                    ← Your source files (permanent)
├── bundle.html             ← Generated artifact (shareable)
├── dist/                   ← Build output (temporary, ignored)
├── node_modules/           ← Dependencies (temporary, ignored)
├── package.json            ← Build config (temporary, ignored)
└── .parcelrc               ← Build config (temporary, ignored)

The .gitignore ensures build artifacts don't get committed to version control.

Step 2: Develop Your Artifact

Edit the files in the src/ directory to build your artifact:

Source files (src/):

• •index.html - Structure and content
• •styles.css - All styling (modern CSS supported)
• •script.js - JavaScript logic and interactivity
• •Additional files - Add more .html, .css, or .js files as needed

Images (src/images/):

• •Place any image files here (PNG, JPEG, GIF, SVG, WebP)
• •Reference them in HTML: <img src="./images/logo.png">
• •Images are automatically:
  • •Bundled into the artifact by Parcel
  • •Base64-encoded in the source metadata
  • •Extractable when unbundling

The files use normal HTML structure with relative paths:

<link rel="stylesheet" href="./styles.css">
<img src="./images/logo.png">
<script src="./script.js"></script>

Everything in src/ works as a standalone static website - open src/index.html in a browser to preview.

Step 3: Bundle to Single HTML File

To bundle into a single HTML artifact:

bash scripts/bundle-vanilla-artifact.sh

Optional versioning:

bash scripts/bundle-vanilla-artifact.sh -v v1
bash scripts/bundle-vanilla-artifact.sh -v v2
bash scripts/bundle-vanilla-artifact.sh --version beta

This creates versioned bundles (e.g., bundle-v1.html, bundle-v2.html) allowing you to:

• •Keep multiple versions for comparison
• •Iterate without overwriting previous versions
• •Share specific versions with users
• •Track evolution of the artifact

Without a version flag, creates bundle.html (overwrites previous).

Performance optimization:

• •First run installs dependencies (~10 seconds)
• •Subsequent runs skip installation (~1 second)
• •Only builds and bundles, much faster for iteration

This creates a self-contained artifact with everything from src/ inlined, plus embedded source metadata.

Requirements: Run from project root (directory containing src/). The src/ directory must contain index.html.

What the script does:

• •Scans the entire src/ directory
• •Collects all HTML, CSS, and JS files
• •Collects all image files from src/images/
• •Skips dependency installation if already present
• •Builds with Parcel (from src/index.html)
• •Inlines all assets into single HTML
• •Embeds concise source metadata with:
  • •Skill identification
  • •Format version marker
  • •LZMA-compressed, base64-encoded files (preserving directory structure)
  • •Binary support for images
• •Lists all bundle versions if using versioning

What gets bundled:

• •All *.html, *.css, *.js files in src/
• •All images in src/images/ (PNG, JPEG, GIF, SVG, WebP)
• •Directory structure preserved in metadata (e.g., "images/logo.png")

Step 4: Share Artifact with User

Share the bundled HTML file with the user by copying it to /mnt/user-data/outputs/ so they can view it as an artifact.

IMPORTANT - When sharing source files:

If the user requests the unbundled/source files, share ONLY the src/ directory:

# Copy the entire src/ directory
cp -r src /mnt/user-data/outputs/project-name-source

✅ The src/ directory contains:

• •index.html, styles.css, script.js
• •Any additional .html, .css, or .js files
• •images/ subdirectory with all images
• •Everything needed as a working static website

❌ NEVER share:

• •dist/ directory (build output, not source)
• •node_modules/ directory (40MB+ dependencies)
• •.parcel-cache/ directory (build cache)
• •package.json, package-lock.json (build config)
• •.parcelrc (build config)
• •bundle.html separately (share OR the src/, not both bundled together)

Best practice: The src/ directory is self-contained and works immediately:

• •Users can open src/index.html in any browser
• •All relative paths work correctly
• •Images display properly
• •No build process needed to view
• •Can be re-bundled if user has the skill

Typical src/ directory size: <50KB even with small images, NOT 40MB+!

Step 5: Unbundle (Optional)

To extract the original source files from a bundled artifact:

bash scripts/unbundle-vanilla-artifact.sh <bundle.html> [output-directory]

Example:

bash scripts/unbundle-vanilla-artifact.sh bundle.html ./my-project-src

Default output directory is ./src if not specified.

This extracts all original source files from the bundle metadata, recreating the src/ directory structure:

What gets extracted:

• •All HTML, CSS, JS files (preserving any subdirectories)
• •All images from src/images/ (as binary files)
• •Directory structure maintained (e.g., images/logo.png)

The extracted src/ directory:

• •Works immediately as a static website
• •Open index.html in browser to view
• •Edit files with any text editor
• •Re-bundle by running the bundle script from parent directory

What the script does:

• •Validates bundle contains source metadata
• •Extracts embedded JSON manifest
• •Decodes LZMA-compressed, base64-encoded files (text and binary)
• •Falls back to raw base64 for older bundles without LZMA compression
• •Recreates directory structure
• •Writes all files to output directory

Note: Works with bundles created using bundle-vanilla-artifact.sh. The unbundle script handles both LZMA-compressed (current format) and uncompressed (legacy format) bundles automatically.

Development Tips

Modular Code Organization

Structure your JavaScript for clarity:

// State
let count = 0;

// DOM elements
const button = document.getElementById('myButton');
const output = document.getElementById('output');

// Functions
function updateDisplay() {
    output.textContent = `Count: ${count}`;
}

function handleClick() {
    count++;
    updateDisplay();
}

// Event listeners
button.addEventListener('click', handleClick);

// Initialize
updateDisplay();

Multiple JavaScript Files

You can split your JavaScript into multiple files:

<!-- In index.html -->
<script src="./utils.js"></script>
<script src="./config.js"></script>
<script src="./script.js"></script>

All files will be:

1. •Bundled into the single HTML artifact
2. •Preserved in the source metadata for unbundling

External Resources

Can use CDN resources in HTML:

<!-- Icons -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css">

<!-- Libraries -->
<script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.0/dist/chart.umd.min.js"></script>

Modern JavaScript Features

All modern JavaScript is supported:

• •ES6+ syntax (arrow functions, destructuring, template literals)
• •Async/await
• •Modules (if using import/export, Parcel handles bundling)
• •Web APIs (Fetch, LocalStorage, Canvas, etc.)

Note: Browser storage APIs work during development but remember artifacts run in a sandboxed environment where localStorage/sessionStorage may not persist.

Round-Trip Workflow

The skill supports a complete round-trip editing workflow:

1. •Bundle → Create artifact from source files
2. •Share → User views artifact in Claude interface
3. •Unbundle → Extract source files from artifact
4. •Edit → Make improvements to source files
5. •Re-bundle → Create updated artifact
6. •Share → User views improved artifact

This enables iterative development and easy maintenance of artifacts.

Self-Documenting Bundles

Bundles created with this skill include a concise metadata comment at the end:

<!-- Metadata generated by the 'vanilla-artifact-builder' skill for Claude (https://github.com/Lerc/JustSomeSkills/tree/main/vanilla-artifact-builder). VANILLA-ARTIFACT-SOURCE-MAP-V1 {...} -->

This annotation:

• •Identifies what created the bundle
• •Links to the skill repository for users who want to install it
• •Contains the version marker and source map in one line
• •Keeps the bundle size minimal while preserving source files

When users encounter a bundle, they can upload it to Claude and ask to extract the source files. Claude will recognize the metadata and use the unbundle script automatically.

Iteration Workflow

The skill supports rapid iteration with versioning:

First iteration:

# Edit src/ files
bash bundle-vanilla-artifact.sh -v v1
# Creates bundle-v1.html
# Share with user

Get feedback, make improvements:

# Edit src/ files based on feedback
bash bundle-vanilla-artifact.sh -v v2
# Creates bundle-v2.html (v1 still exists)
# Share new version

Benefits of versioned bundles:

• •Compare versions side-by-side
• •Roll back if needed
• •Show evolution to stakeholders
• •Keep working versions during experimentation
• •Fast: ~1 second after first build (dependencies cached)

Version naming suggestions:

• •Sequential: v1, v2, v3
• •Descriptive: beta, final, updated
• •Dated: 2024-10-19, oct19
• •Feature-based: with-images, responsive

Sharing versioned bundles:

# Share specific version
cp bundle-v2.html /mnt/user-data/outputs/artifact-v2.html

# Share all versions for comparison
cp bundle-v*.html /mnt/user-data/outputs/

# Share latest with generic name
cp bundle-v2.html /mnt/user-data/outputs/my-artifact.html

The .gitignore doesn't exclude bundle files, so versioned bundles can be tracked in version control if desired.

Common Patterns

Interactive Visualizations

Separate concerns for data, rendering, and interaction.

Form-Based Applications

Keep validation logic, state management, and UI updates in separate functions.

Games and Animations

Use requestAnimationFrame, separate game loop from rendering logic.

Data Dashboards

Fetch data, process it, and render visualizations with clean separation.

Troubleshooting

Build fails: Ensure index.html exists in project root and properly links to CSS/JS files.

Bundled file too large: Consider optimizing images, minifying code, or splitting into multiple artifacts.

JavaScript not working: Check browser console in bundled file. Ensure proper event listener setup and DOM element selection.

Styling issues: Verify CSS selectors match HTML structure. Check for specificity conflicts.

Unbundle fails with "No source metadata found": The bundle was created with an older version of the bundling script. Only bundles created with the updated script contain metadata.

Unbundled files don't match originals: This should never happen. If it does, it indicates a bug in the base64 encoding/decoding process.

User received 40MB+ tar.gz with node_modules: This is incorrect! Never share the entire project directory. Only share the actual source files (*.html, *.css, *.js). The dist/, node_modules/, and build configuration files should never be shared with users. See "Step 4: Share Artifact with User" for correct file sharing practices.