You can decode the base64 image using following method .

EDITED

To strip off the header

let base64String = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgA'; // Not a real image
// Remove header
let base64Image = base64String.split(';base64,').pop();

To write to a file

import fs from 'fs';
fs.writeFile('image.png', base64Image, {encoding: 'base64'}, function(err) {
    console.log('File created');
});

Note :- Don’t forget the {encoding: 'base64'} here and you will be good to go.

One possible problem:

"Error: Invalid base64 string"

To debug, try replacing 1st line with: var base64Str = "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==";

Another:

An incorrect path as a logical error, runs code without error but not saving the image file as it should. Ie, if the path points to a non-existant directory, misspelled directory or a inaccessable directory.

To debug, try replacing 2nd line with var path ='./'; so it will save in the script directory. Note that '/' leads to no file saved, and an empty string leads to error "Missing mandatory arguments..."

You can use png-to-jpeg module. Assuming the 'data' is in string form :

const fs = require("fs");

const pngToJpeg = require('png-to-jpeg');
const imgStr = 'data:image/png;base64, iVBORw0KGgoAAAANSUhEUgAAAfQAAAH0CAYAAADL1t.....';

const buffer = new Buffer(imgStr.split(/,\s*/)[1],'base64');
pngToJpeg({quality: 90})(buffer).then(output => fs.writeFileSync("./some-file.jpeg", output));

BufferList is obsolete, as its functionality is now in Node core. The only tricky part here is setting request not to use any encoding:

var request = require('request').defaults({ encoding: null });

request.get('http://tinypng.org/images/example-shrunk-8cadd4c7.png', function (error, response, body) {
    if (!error && response.statusCode == 200) {
        data = "data:" + response.headers["content-type"] + ";base64," + Buffer.from(body).toString('base64');
        console.log(data);
    }
});