How can I download and save a file using the Fetch API? (Node.js)

Question

I have the url to a possibly large (100+ Mb) file, how do I save it in a local directory using fetch?

I looked around but there don't seem to be a lot of resources/tutorials on how to do this.

Thank you!

I'm creating an Electron app, fetch is supported. Why fetch instead of pure http, because it's a lot easier to use (or so it seemed so far). — Gloomy, Jun 03 '16 at 12:53
If someone looked for a way to save file using fetch api but in browser (and came across this answer) then please take a look here: http://stackoverflow.com/a/42274086/350384 — Mariusz Pawelski, Feb 16 '17 at 12:36

score 66 · Answer 1 · edited Oct 27 '20 at 19:24

66

Using the Fetch API you could write a function that could download from a URL like this:

const downloadFile = (async (url, path) => {
  const res = await fetch(url);
  const fileStream = fs.createWriteStream(path);
  await new Promise((resolve, reject) => {
      res.body.pipe(fileStream);
      res.body.on("error", reject);
      fileStream.on("finish", resolve);
    });
});

edited Oct 27 '20 at 19:24

machineghost

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answered Jul 12 '18 at 09:51

code_wrangler

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3

You could even make it a little shorter by writing `res.body.on('error', reject);` and `fileStream.on('finish', resolve);`. – Ricki-BumbleDev Jun 14 '20 at 10:21
This gives an error: res.body.pipe is not a function. NodeJS v18 – tinkerr Apr 24 '22 at 06:53

score 21 · Answer 2 · answered Dec 27 '18 at 03:56

21

If you want to avoid explicitly making a Promise like in the other very fine answer, and are ok with building a buffer of the entire 100+ MB file, then you could do something simpler:

const fetch = require('node-fetch');
const {writeFile} = require('fs');
const {promisify} = require('util');
const writeFilePromise = promisify(writeFile);

function downloadFile(url, outputPath) {
  return fetch(url)
      .then(x => x.arrayBuffer())
      .then(x => writeFilePromise(outputPath, Buffer.from(x)));
}

But the other answer will be more memory-efficient since it's piping the received data stream directly into a file without accumulating all of it in a Buffer.

answered Dec 27 '18 at 03:56

Ahmed Fasih

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I have tried this code but got error...I got error [Error: EISDIR: illegal operation on a directory, open 'D:\Work\repo\'] { errno: -4068, code: 'EISDIR', syscall: 'open', path: 'D:\\Work\\repo\\' } – Scott Jones May 23 '22 at 09:08
@ScottJones `EISDIR` means "Error: IS Directory": you're giving Node a directory when it expects a file. Just use `d:\work\repo\file.txt` for example – Ahmed Fasih May 23 '22 at 16:45

Ihor Sakailiuk · Answer 3 · 2022-01-04T16:50:21.653

6

const {createWriteStream} = require('fs');
const {pipeline} = require('stream/promises');
const fetch = require('node-fetch');

const downloadFile = async (url, path) => pipeline(
    (await fetch(url)).body,
    createWriteStream(path)
);

edited Jan 04 '22 at 16:50

answered Aug 19 '20 at 16:48

Ihor Sakailiuk

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I get error `TypeError: Cannot read property 'on' of undefined at destroyer (internal/streams/pipeline.js:23:10)` – Codler Oct 17 '20 at 07:35

How can I download and save a file using the Fetch API? (Node.js)

3 Answers3

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