lamers/MIME

A simple utility for working with MIME types and file extensions in JavaScript/TypeScript. This module provides two functions:

• mimeType: Determines the MIME type of a file based on its extension.
• extension: Retrieves the file extension associated with a specific MIME type.

Features

• Easily map file extensions to MIME types.
• Supports custom mappings via the MIMETYPES object.
• Handles unknown MIME types or extensions gracefully with fallback behavior.

Table of Contents

• Installation
• Usage
  • mimeType
  • extension
• Examples
• License

Installation

To use this utility, include it in your project:

npm install lamers-mime

Usage

mimeType(filename: string): string

This function determines the MIME type of a file based on its extension. If the extension is not found in the MIMETYPES object, it returns a default value of 'application/octet-stream'.

Parameters

• filename: The name of the file (string).

Returns

• A string representing the MIME type of the file.

Example

import { mimeType } from './lamers-mime';

console.log(mimeType('picture.jpg')); // Output: 'image/jpeg'
console.log(mimeType('unknownfile.xyz')); // Output: 'application/octet-stream'

extension(mime: string): string | null

This function retrieves all file extensions associated with a MIME type. If the MIME type is not found, it returns null.

Parameters

• mime: The MIME type to look up (string).

Returns

• The file extensions (string[]) or null if not found.

Example

import { extension } from 'lamers-mime';

console.log(extension('image/jpeg')); // Output: ['jpg']
console.log(extension('application/xml')); // Output: null

Examples

Here are a few examples to demonstrate how this utility works:

Example 1: Mapping File Extensions to MIME Types

import { mimeType } from './lamers-mime';

console.log(mimeType('document.txt')); // Output: 'text/plain'
console.log(mimeType('image.jpeg'));   // Output: 'image/jpeg'
console.log(mimeType('unknown.ext'));  // Output: 'application/octet-stream'

Example 2: Mapping MIME Types to Extensions

import { extension } from './lamers-mime';

console.log(extension('text/plain'));  // Output: ['txt']
console.log(extension('application/json')); // Output: ['json']
console.log(extension('unknown/mime')); // Output: null

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contributing

Contributions are welcome! If you have suggestions, bug fixes, or improvements, please create a pull request or open an issue.

Contact

If you have any questions or feedback, feel free to reach out via GitHub issues or email.