How to download a file with Node.js (without using third-party libraries)?

You can create an HTTP GET request and pipe its response into a writable file stream:

const http = require('http'); // or 'https' for https:// URLsconst fs = require('fs');const file = fs.createWriteStream("file.jpg");const request = http.get("http://i3.ytimg.com/vi/J---aiyznGQ/mqdefault.jpg", function(response) {  response.pipe(file);});

If you want to support gathering information on the command line--like specifying a target file or directory, or URL--check out something like Commander.

Don't forget to handle errors! The following code is based on Augusto Roman's answer.

var http = require('http');var fs = require('fs');var download = function(url, dest, cb) {  var file = fs.createWriteStream(dest);  var request = http.get(url, function(response) {    response.pipe(file);    file.on('finish', function() {      file.close(cb);  // close() is async, call cb after close completes.    });  }).on('error', function(err) { // Handle errors    fs.unlink(dest); // Delete the file async. (But we don't check the result)    if (cb) cb(err.message);  });};

As Michelle Tilley said, but with the appropriate control flow:

var http = require('http');var fs = require('fs');var download = function(url, dest, cb) {  var file = fs.createWriteStream(dest);  http.get(url, function(response) {    response.pipe(file);    file.on('finish', function() {      file.close(cb);    });  });}

Without waiting for the finish event, naive scripts may end up with an incomplete file.

Edit: Thanks to @Augusto Roman for pointing out that cb should be passed to file.close, not called explicitly.