async-multipart-parser

A zero-dependency streaming multipart parser built on async iterators.

Usage

import {parseMultipart} from 'async-multipart-parser'

for await (const part of parseMultipart(request, {
  contentType: request.headers['content-type']
})) {
  console.log(part.name, part.filename, part.headers)

  for await (const chunk of part.body) {
    // Each chunk is a Uint8Array and can be streamed directly to a file
    // or object storage without buffering the complete part in memory.
  }
}

API

The only public API is parseMultipart(stream, config).

stream may be a Node.js Readable, a Web ReadableStream, or any AsyncIterable. The following configuration options are supported:

• boundary: the multipart boundary.
• contentType: used to extract the boundary when boundary is omitted.
• maxHeaderSize: maximum header size for each part; defaults to 64 KiB.
• maxParts: maximum number of parts; unlimited by default.

Each part contains headers, optional name and filename properties, and a streaming body exposed as an AsyncIterable<Uint8Array>.

Consume the current part's body before advancing to the next part. If the body is left unconsumed, the parser discards it automatically when the outer iterator advances.