content-type-parser

What is content-type-parser?

The content-type-parser npm package is used to parse and handle Content-Type headers in HTTP requests and responses. It helps in extracting the media type, parameters, and other relevant information from Content-Type strings.

What are content-type-parser's main functionalities?

Parsing Content-Type

This feature allows you to parse a Content-Type string and extract the media type and parameters. In the example, the Content-Type 'application/json; charset=utf-8' is parsed to extract the type 'application/json' and the charset parameter 'utf-8'.

const contentTypeParser = require('content-type-parser');
const parsed = contentTypeParser('application/json; charset=utf-8');
console.log(parsed.type); // 'application/json'
console.log(parsed.parameters.charset); // 'utf-8'

Handling Invalid Content-Type

This feature demonstrates how the package handles invalid Content-Type strings. If the Content-Type string is invalid, an error is thrown, which can be caught and handled appropriately.

const contentTypeParser = require('content-type-parser');
try {
  const parsed = contentTypeParser('invalid-content-type');
} catch (error) {
  console.error('Invalid Content-Type:', error.message);
}

Comparing Media Types

This feature allows you to compare two parsed Content-Type objects to check if they represent the same media type. In the example, 'application/json' and 'application/json; charset=utf-8' are considered equal.

const contentTypeParser = require('content-type-parser');
const parsed1 = contentTypeParser('application/json');
const parsed2 = contentTypeParser('application/json; charset=utf-8');
console.log(parsed1.isEqual(parsed2)); // true

Other packages similar to content-type-parser

content-type

The content-type package provides similar functionality for parsing and formatting Content-Type headers. It offers methods to parse Content-Type strings into objects and format objects back into strings. Compared to content-type-parser, it has a simpler API and is widely used in the Node.js ecosystem.

media-typer

The media-typer package is another alternative for parsing and formatting media types. It focuses on parsing media type strings and formatting them back into strings. It is more lightweight compared to content-type-parser and is often used in conjunction with other HTTP-related packages.

mime-types

The mime-types package provides utilities for handling MIME types, including methods to look up MIME types based on file extensions and vice versa. While it does not focus solely on Content-Type parsing, it offers a broader range of MIME type-related functionalities compared to content-type-parser.

README

Parse Content-Type Header Strings

This package will parse the Content-Type header field into an introspectable data structure, whose parameters can be manipulated:

const contentTypeParser = require("content-type-parser");

const contentType = contentTypeParser(`Text/HTML;Charset="utf-8"`);

console.assert(contentType.toString() === "text/html;charset=utf-8");

console.assert(contentType.type === "text");
console.assert(contentType.subtype === "html");
console.assert(contentType.get("charset") === "utf-8");

contentType.set("charset", "windows-1252");
console.assert(contentType.get("charset") === "windows-1252");
console.assert(contentType.toString() === "text/html;charset=windows-1252");

console.assert(contentType.isHTML() === true);
console.assert(contentType.isXML() === false);
console.assert(contentType.isText() === true);

Note how parsing will lowercase the type, subtype, and parameter name tokens (but not parameter values).

If the passed string cannot be parsed as a content-type, contentTypeParser will return null.

ContentType instance API

This package's main module's default export will return an instance of the ContentType class, which has the following public APIs:

Properties

• type: the top-level media type, e.g. "text"
• subtype: the subtype, e.g. "html"
• parameterList: an array of { separator, key, value } pairs representing the parameters. The separator field contains any whitespace, not just the ; character.

Parameter manipulation

In general you should not directly manipulate parameterList. Instead, use the following APIs:

• get("key"): returns the value of the parameter with the given key, or undefined if no such parameter is present
• set("key", "value"): adds the given key/value pair to the parameter list, or overwrites the existing value if an entry already existed

Both of these will lowercase the keys.

MIME type tests

• isHTML(): returns true if this instance's MIME type is the HTML MIME type, "text/html"
• isXML(): returns true if this instance's MIME type is an XML MIME type
• isText(): returns true if this instance's top-level media type is "text"

Serialization

• toString() will return a canonicalized representation of the content-type, re-built from the parsed components

Credits

This package was originally based on the excellent work of @nicolashenry, in jsdom. It has since been pulled out into this separate package.