mime-db-lite

A tiny, lightweight, portable JavaScript module to query the complete mime-db (a popular Media-type / MIME-type / Content-type database). Data is actually sourced from mime-db-cdn, which mirrors mime-db with added features.

🚀 Consumes less run-time memory by fetching data as and when needed, with optional caching. Ideal for low footprint applications.

🚀 Cross-platform: Runs on browsers, server-side (e.g. NodeJS) or serverless (e.g. Cloudflare Workers V8 isolates).

🚀 Standard: ESM.

🚀 Promise-based; exports async methods.

🚀 Accepts custom fetch() method, if any.

Install and import

For browsers:

1<script type="module">
2    import DB from 'https://cdn.jsdelivr.net/npm/mime-db-lite@2.0.0/index.min.js';
3    // Above, replace 2.0.0 with the actual version you'd be using, or use 'latest'
4    
5    // Your code here ...
6</script>

For Node.js:

Install as

1npm install mime-db-lite

Import as

1import DB from 'mime-db-lite';

Instantiation, custom fetch() and LRU cache

Create an instance of the imported DB class to use the fetch() API provided by the runtime and forgo caching.

👉 For browsers, the native fetch() will still use the HTTP-cache.

1const db = new DB();

To use an in-memory cache, instantiate as:

1const db = new DB({ cacheMaxEntries: <Integer> });

<Integer> denotes the maximum number of entries the cache can store, beyond which the LRU entries will be evicted to make just enough space.

👉 Using an LRU cache claims more run-time memory in return for faster lookups. For browsers this may be unnecessary, because browser-native fetch() already uses HTTP-cache by default.

To use a custom fetch() method, e.g. async function custFetch (url) { ... }, instantiate as:

1const db = new DB({ fetch: custFetch });

or, use an arrow function

1const db = new DB({
2    fetch: async (url) => {
3        // Your code here
4    } 
5});

API

db.mimeToExtensions(mimeType) or its alias db.getExtensions(mimeType)

Returns a promise that fulfills with an array of file-extensions.

mimeType

String representing a MIME-type with structure:

type/subtype

type/subtype;parameter=value

👉 The returned promise is rejected with Not Found error if the provided mimeType is unavailable in mime-db.

Examples:

1console.log(await db.mimeToExtensions('application/mp4'));
2// Prints [ 'mp4', 'mpg4', 'mp4s', 'm4p' ]
3
4console.log(await db.getExtensions('application/javascript; charset=utf-8'));
5// Prints [ 'js' ]

db.extensionToMimes(extension) or its alias db.getTypes(extension)

Returns a promise that fulfills with an array of MIME-types. Note that this array of MIME-types is sorted in descending order of importance according to the same logic used by mime-types. If only one MIME-type is required, simply choose the first element from the array, or use the db.getType() method.

extension

String representing either of

• path, e.g. dir/subdir/file.ext
• file-extension with or without the leading dot, e.g. mp4, .mp4
• file-name, e.g. file.mp4, file.version.1.2.0.mp4

👉 The returned promise is rejected with Not Found error if the provided mimeType is unavailable in mime-db.

Examples:

1console.log(await db.extensionToMimes('dir/subdir/path.version.js'));
2
3console.log(await db.getTypes('js'));
4
5console.log(await db.getTypes('.js'));
6
7// Prints [ 'application/javascript', 'text/javascript' ]

db.extensionToMime(extension) or its alias db.getType(extension)

Same as db.getTypes() above but the returned promise resolves with only a single MIME-type instead of an array. The returned MIME-type has the highest score according to the logic used by mime-types.

Examples:

1console.log(await db.getType('.deb'));
2// Prints 'application/x-debian-package'

db.query(mimeType)

Returns a promise that fulfills with the mime-db data object for the provided MIME-type.

mimeType

String representing a MIME-type in the form: type/subtype

👉 The returned promise is rejected with Not Found error if the provided mimeType is unavailable in mime-db.

Examples:

1console.log(JSON.stringify(await db.query('application/javascript')));
2// Prints '{"source":"apache","charset":"UTF-8","compressible":true,"extensions":["js"]}'

DB.mimeDbCdnVersion

A constant that stores the mime-db-cdn release version data is fetched from.

DB.cdnBase

A constant that stores the CDN via which data is accessed.

Contribute

To register new media types in the database, contribute directly to mime-db.

If you like this project, you can show your appreciation by

• giving it a star ⭐
• sponsoring me through 👇

Thank you 💚.