@prexjs/content-type

Create and parse HTTP Content-Type headers and media types according to RFC 9110.

@prexjs/content-type is a high-performance utility for parsing and formatting HTTP Content-Type headers and MIME types according to RFC 9110 standards.

Features

• Parse Content-Type header strings into type and parameter objects.
• Format structured objects into valid Content-Type header strings with proper quote escaping.
• Validate media types and token characters per RFC 9110.
• Fast ASCII character bitmask lookup for high throughput.
• Zero runtime dependencies.
• Dual ES Module (.mjs) and CommonJS (.cjs) support with TypeScript definitions.

Installation

Install using your preferred package manager:

# npm
npm install @prexjs/content-type

# pnpm
pnpm add @prexjs/content-type

# Yarn
yarn add @prexjs/content-type

# Bun
bun add @prexjs/content-type

Quick start

import contentType from '@prexjs/content-type';

// Parse a Content-Type header
const parsed = contentType.parse('text/html; charset=utf-8');
console.log(parsed.type); // 'text/html'
console.log(parsed.parameters); // { charset: 'utf-8' }

// Format an object to a header string
const header = contentType.format({
  type: 'application/json',
  parameters: { charset: 'utf-8' },
});
console.log(header); // 'application/json; charset=utf-8'

Both default and named exports are supported:

import contentType, {
  parse,
  format,
  isTypeValid,
  isTokenValid,
  type ContentType,
  type ParsedContentType,
  type Parameters,
  type ParseOptions,
} from '@prexjs/content-type';

Examples

Parsing headers with parameters

import { parse } from '@prexjs/content-type';

const obj = parse('multipart/form-data; boundary="something_special"');
console.log(obj.type); // 'multipart/form-data'
console.log(obj.parameters.boundary); // 'something_special'

Formatting headers

import { format } from '@prexjs/content-type';

const header = format({
  type: 'image/svg+xml',
  parameters: {
    charset: 'utf-8',
  },
});
// 'image/svg+xml; charset=utf-8'

Type and token validation

import { isTypeValid, isTokenValid } from '@prexjs/content-type';

console.log(isTypeValid('application/json')); // true
console.log(isTypeValid('invalid type')); // false

console.log(isTokenValid('charset')); // true
console.log(isTokenValid('token with spaces')); // false

Compatibility

@prexjs/content-type is designed for JavaScript and TypeScript projects. It is distributed with ES Modules (.mjs), CommonJS (.cjs), and TypeScript declarations. It runs in any modern JavaScript runtime (Node.js, Deno, Bun, browser) without external dependencies.

License

This project is licensed under the MIT License. See LICENSE for the full license text.

Related projects

• prex.js — prex.js monorepo and ecosystem.