How To Download A File With Node.js

Photo by Savannah Wakefield on Unsplash

Over the weekend I made a dependency update of my time tracking app Tie Tracker (PWA / GitHub).

In this particular tool, I defer the heavy work to Web Workers so that the UI does not find itself in a blocking state.

Because the app is meant to work offline and, is available in the App Store and Google Play, I did not import the required workers dependencies through a CDN but, locally.

The app itself is developed with React but, I implemented the workers with vanilla JavaScript and no package manager to handle their dependencies.

Therefore, I had to come with a solution to update the libs with aNode.js script .

Node Fetch

There is no window.fetch like API in Node.js but, there is a light-weight module that brings such capabilities. Thats why I used node-fetch to implement the download of the file.

npm i node-fetch --save-dev

Script

The script I developed to update my dependencies is the following:

const {createWriteStream} = require('fs');const {pipeline} = require('stream');const {promisify} = require('util');const fetch = require('node-fetch');const download = async ({url, path}) => {  const streamPipeline = promisify(pipeline);  const response = await fetch(url);  if (!response.ok) {    throw new Error(`unexpected response ${response.statusText}`);  }  await streamPipeline(response.body, createWriteStream(path));};(async () => {  try {    await download({      url: 'https://unpkg.com/...@latest/....min.js',      path: './public/workers/libs/....min.js',    });  } catch (err) {    console.error(err);  }})();

The above download function uses a stream pipeline to download a file, as displayed in the node-fetch README, and the built-in fs module to write the output to the file system.

Top Level Await is available as of Node.js v14.8.0 but, I used an immediate function because I integrated it in a chain in which it was not available yet.

Thats it

Continue Reading

If you want to read more about React and Web Workers, I published back to back three blog posts about it last year .

• React and Web Workers
• React, Web Workers, and IndexedDB
• React, Web Workers, IndexedDB and ExcelJS

To infinity and beyond!

David

You can reach me on Twitter or my website.

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