Send-ranges NPM

send-ranges

Express middleware for handling HTTP range requests. Requires node 18 or higher.

Installation

npm install --save send-ranges

Usage

const path = require('path')
const fse = require('fs-extra')
const express = require('express')
const sendRanges = require('send-ranges')
const app = express()

const mp3Path = path.join(__dirname, 'mp3s')

async function retrieveFile(request) {
  const filename = request.params.filename
  if (!/\.mp3$/.test(filename)) {
    return null // Falsey values will call the next handler in line
  }

  const filePath = path.join(mp3Path, filename)
  const getStream = (range) => fs.createReadStream(filePath, range)
  const type = 'audio/mpeg'
  const stats = await fse.stat(filePath)

  return {getStream, type, size: stats.size}
}

app.get('/:filename', sendRanges(retrieveFile), (req, res) => {
  // If we got here, this was not a range request, or the `retrieveFile` handler
  // returned a falsey value
  res.sendFile(path.join(mp3Path, req.params.filename))
})

app.listen(3000, () => {
  console.log('Example app listening on port 3000!')
})

Options

Exported function accept an options config object that will be passed to range-parser. In addition that, this options object accept some send-ranges specific ones:

Pre-send hook

You can pass a beforeSend function as an option. This is handy if you want to:

Handle the response sending yourself
Use metadata fetched in the file retriever to set headers on the response
Validate and possibly cancel the response before it is sent

The retrieveFile function can return an additional metadata property which will be passed to the beforeSend function. Here's an example:

async function retrieveFile(request) {
  const file = await someObjectStore.getFile(request.path)
  const size = file.size
  const metadata = file.metadata
  const type = metadata.contentType
  const getStream = (range) => file.createReadStream(range)
  return {getStream, size, metadata, type}
}

async function beforeSend(info, cb) {
  const {request, response, metadata, sourceStream} = info
  response.set('Last-Modified', new Date(metadata.updated).toUTCString())
  cb()
}

app.get('/*', sendRanges(retrieveFile, {beforeSend}))

Maximum number of ranges

By default, up to two ranges are allowed. The limit can be adjusted with the maxRanges option:

sendRanges(retrieveFile, {maxRanges: 4})

intersectRanges

Optional function that allow to modify the list of ranges to be returned. This can be used for example if the data is not fully available because your file has holes in it. It will be called with an object with the same metadata field used for the beforeSend() optional function, and a ranges field with the list of ranges.