Download to file & download to buffer Typescript, Node 12.x, support for redirects. http/https

downloads.ts

import fs from 'fs'
import https from 'https'
import http from 'http'
import { basename } from 'path'
import { URL } from 'url'

const TIMEOUT = 10000
const MAX_DOWNLOAD_FILE_SIZE = 1024 * 1024 * 200 // 200MB

export function downloadAsBuffer (url: string): Promise<Buffer> {
  const uri = new URL(url)
  const pkg = url.toLowerCase().startsWith('https:') ? https : http

  return new Promise((resolve, reject) => {
    const request = pkg.get(uri.href).on('response', (res) => {
      if (res.statusCode === 200) {
        const chunks:Uint8Array[] = []
        const fileSize = parseInt(res.headers['content-length'] as string, 10)
        if (fileSize > MAX_DOWNLOAD_FILE_SIZE) {
          reject(new Error(`File is too big for download. The file cannot exceed ${MAX_DOWNLOAD_FILE_SIZE} bytes`))
          return
        }
        res
          .on('data', (chunk: Buffer) => {
            chunks.push(chunk)
          })
          .on('end', () => {
            if (!res.complete) {
              reject(new Error('The connection was terminated while the file was still being sent'))
            }
            resolve(Buffer.concat(chunks))
          })
          .on('error', (err) => {
            reject(err)
          })
      } else if (res.statusCode === 302 || res.statusCode === 301) {
        // Recursively follow redirects, only a 200 will resolve.
        downloadAsBuffer(res.headers.location as string).then(() => resolve())
      } else {
        reject(new Error(`Download request failed, response status: ${res.statusCode} ${res.statusMessage}`))
      }
    })
    request.setTimeout(TIMEOUT, function () {
      request.abort()
      reject(new Error(`Request timeout after ${TIMEOUT / 1000.0}s`))
    })
  })
}

/**
 * Downloads specified `url` as a file and store it to `dest`
 * @param url The URL of the file for download
 * @param dest THe destination path and file name
 */
export function downloadAsFile (url: string, dest?: string): Promise<string> {
  const uri = new URL(url)
  if (!dest) {
    dest = basename(uri.pathname)
  }
  const pkg = url.toLowerCase().startsWith('https:') ? https : http

  return new Promise((resolve, reject) => {
    const request = pkg.get(uri.href).on('response', (res) => {
      if (res.statusCode === 200) {
        const fileSize = parseInt(res.headers['content-length'] as string, 10)
        if (fileSize > MAX_DOWNLOAD_FILE_SIZE) {
          reject(new Error(`File is too big for download. The file cannot exceed ${MAX_DOWNLOAD_FILE_SIZE} bytes`))
          return
        }

        const file = fs.createWriteStream(dest as string, { flags: 'w' })
        res
          .on('end', () => {
            if (!res.complete) {
              fs.unlink(dest as string, () => reject(new Error('The connection was terminated while the file was still being sent')))
            }
            file.end()
            // console.log(`${uri.pathname} downloaded to: ${path}`)
            resolve(dest)
          })
          .on('error', (err) => {
            file.destroy()
            fs.unlink(dest as string, () => reject(err))
          }).pipe(file)
      } else if (res.statusCode === 302 || res.statusCode === 301) {
        // Recursively follow redirects, only a 200 will resolve.
        downloadAsFile(res.headers.location as string, dest).then(() => resolve())
      } else {
        reject(new Error(`Download request failed, response status: ${res.statusCode} ${res.statusMessage}`))
      }
    })
    request.setTimeout(TIMEOUT, function () {
      request.abort()
      reject(new Error(`Request timeout after ${TIMEOUT / 1000.0}s`))
    })
  })
}

export default downloadAsFile