fetch-multipart-parser

fetch-multipart-parser is a streaming multipart parser for JavaScript's fetch API.

Features

This package is a streaming multipart parser for JavaScript's fetch API, making it easy to parse incoming Request bodies that are generated by <form enctype="multipart/form-data"> in the browser.

Installation

$ npm install fetch-multipart-parser

Usage

import { MultipartParseError, parseMultipartFormData } from 'fetch-multipart-parser';

function handleMultipartRequest(request: Request): void {
  try {
    // The parser `yield`s each part as a MultipartPart as it becomes available.
    for await (let part of parseMultipartFormData(request)) {
      console.log(part.name);
      console.log(part.filename);
      console.log(part.mediaType);

      if (/^text\//.test(part.mediaType)) {
        console.log(new TextDecoder().decode(part.content));
      } else {
        // part.content is binary data, save it to a file
      }
    }
  } catch (error) {
    if (error instanceof MultipartParseError) {
      console.error('Failed to parse multipart/form-data:', error.message);
    } else {
      console.error('An unexpected error occurred:', error);
    }
  }
}

Benchmark

The results of running the benchmarks on my laptop:

Platform: Darwin (23.5.0)
CPU: Apple M2 Pro
Node.js v20.15.1
Date: 7/26/2024, 4:04:11 PM
┌────────────────────────┬──────────────────┬──────────────────┬──────────────────┬───────────────────┐
│ (index)                │ 1 small file     │ 1 large file     │ 100 small files  │ 5 large files     │
├────────────────────────┼──────────────────┼──────────────────┼──────────────────┼───────────────────┤
│ fetch-multipart-parser │ '0.02 ms ± 0.13' │ '2.03 ms ± 0.75' │ '0.34 ms ± 0.15' │ '21.86 ms ± 2.24' │
│ busboy                 │ '0.03 ms ± 0.09' │ '4.11 ms ± 0.20' │ '0.23 ms ± 0.03' │ '45.13 ms ± 3.22' │
│ @fastify/busboy        │ '0.03 ms ± 0.08' │ '2.05 ms ± 0.20' │ '0.38 ms ± 0.04' │ '27.88 ms ± 2.84' │
└────────────────────────┴──────────────────┴──────────────────┴──────────────────┴───────────────────┘