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..."