imguri

Convert local and remote images to data URI scheme for inline embedding.

Features

• ES modules with dual CJS/ESM support
• Local files and HTTP/HTTPS URLs
• Concurrent batch processing
• Path traversal protection
• Native fetch API, no deprecated dependencies

Requirements: Node.js >= 18.0.0

Installation

npm install imguri

Usage

Single File

import { encodeSingle } from 'imguri';

// Local file
const uri = await encodeSingle('logo.png');
console.log(uri); // data:image/png;base64,...

// Remote URL
const uri = await encodeSingle('https://example.com/image.jpg');

// With options
const uri = await encodeSingle('large.png', {
  sizeLimit: 256000, // 250KB
  force: true, // override limit
});

Batch Processing

import { encode } from 'imguri';

const results = await encode(['icon1.png', 'icon2.png', 'https://example.com/logo.jpg'], {
  concurrency: 5,
});

for (const [path, result] of results) {
  if (result.error) {
    console.error(path, result.error.message);
  } else {
    console.log(path, result.data.substring(0, 50) + '...');
  }
}

CommonJS

const { encodeSingle } = require('imguri');

(async () => {
  const uri = await encodeSingle('image.png');
  console.log(uri);
})();

API

encodeSingle(path, options?)

Encodes a single file or URL to data URI.

• path string - File path or HTTP/HTTPS URL
• options object
  • sizeLimit number - Max bytes (default: 131072 / 128KB)
  • force boolean - Override size limit (default: false)
  • timeout number - HTTP timeout ms (default: 20000)

Returns Promise<string> - Data URI string

Throws if file not found, size exceeded, or network error.

encode(paths, options?)

Encodes multiple files/URLs with concurrent processing.

• paths string | string[] - Path(s) to encode
• options object - Same as encodeSingle, plus:
  • concurrency number - Max parallel ops (default: 10)

Returns Promise<Map<string, EncodeResult>> where EncodeResult is:

{
  data: string | null,  // Data URI or null if error
  error: Error | null   // Error or null if success
}

encodeLegacy(paths, options, callback)

Callback-based API for v0.x compatibility. Deprecated, will be removed in v2.0.

Configuration

Option	Type	Default	Description
sizeLimit	number	131072	Max file size in bytes (128KB)
timeout	number	20000	HTTP timeout in milliseconds
concurrency	number	10	Max concurrent operations
force	boolean	false	Override size limit

Security

Path validation prevents directory traversal attacks (../ is blocked). Absolute paths are allowed but can access any readable file - validate user input in production.

For HTTP URLs, content-type validation ensures only images are processed. Size limits prevent memory exhaustion.

Migration from v0.x

v1.0 replaces callbacks with promises and changes result format from object to Map. Use encodeLegacy() for backward compatibility or update to promise-based API:

// v0.x
imguri.encode(['file.png'], opts, (err, results) => { ... });

// v1.0
const results = await encode(['file.png'], opts);
for (const [path, result] of results) { ... }

See CHANGELOG.md for complete migration guide.

How It Works

Two-layer architecture separates business logic from I/O:

• Core layer: Base64 encoding and data URI formatting
• Adapter layer: File system operations and HTTP client
• Main module: Coordinates adapters, validates paths, manages concurrency

Data flows: Adapter → Validation → Encoder → Data URI string

Development

npm install      # Install dependencies
npm test         # Run tests (54 tests, 89% coverage)
npm run lint     # Check code style
npm run build    # Build CJS/ESM bundles

Documentation

• Technical Blog - Architecture deep dive
• Changelog - Version history
• Security Policy - Vulnerability reporting

License

MIT License