This is a library for parsing MIME multipart messages, such as those used in HTTP requests and email messages, written in TypeScript. It provides an easy-to-use async generator that returns the parsed headers and body of each part in a multipart message. Nested multipart messages are supported.
- Parses multipart messages according to the specification
- Supports nested multipart messages
- Lightweight and fast
- Written in TypeScript, but can be used with plain JavaScript as well
- Well-tested
You can install the library using either npm
or yarn
:
npm install @apeleghq/multipart-parser
yarn add @apeleghq/multipart-parser
The library exports the function parseMultipartMessage
, which returns an async
generator that yields objects with the headers and body (as a Uint8Array
) of
each part in the multipart message.
This function takes a ReadableStream
and a boundary string as arguments, and
returns an asynchronous generator that yields objects with the following
properties:
-
headers
: aHeaders
object containing the headers of the current part -
body
: aUint8Array
containing the body of the current part, ornull
if the part is empty. -
parts
: a nested iterator of the same structure for any parts within the current part, if the part'sContent-Type
header indicates that it is a multipart message.
A regular expression that can be used to validate a boundary string.
A regular expression that can be used to extract a boundary string from a
Content-Type
header.
encodeMultipartMessage(boundary: string, msg: AsyncIterable<TDecodedMultipartMessage>): ReadableStream<ArrayBuffer>
This function takes a boundary string and an array of messages as arguments and returns a ReadableStream
that can be read to obtain a multipart message.
TDecodedMultipartMessage
is defined as an object with the following fields:
-
headers
: aHeaders
object containing the headers of the current part -
body
(optional): The body of the current part, ornull
if the part is empty. It can be any of the following types:ArrayBuffer
,Blob
,ReadableStream
or any typed array, such asUint8Array
. -
parts
(optional): An async or sync iterable of one element or more of the same type (TDecodedMultipartMessage
), for nested messages. If bothbody
andparts
are specified,body
takes precedence.
import { parseMultipartMessage } from '@apeleghq/multipart-message-parser';
const decoder = new TextDecoder();
const stream = ... // a ReadableStream containing the multipart message
const boundary = 'my-boundary'; // the boundary of the multipart message
for await (const part of parseMultipartMessage(stream, boundary)) {
console.log(part.headers.get('content-type'));
console.log(decoder.decode(part.body));
}
We welcome contributions to this project! Feel free to submit a pull request or open an issue if you find a bug or have a feature request.
This library is licensed under the ISC License, see LICENSE for more information.