Cropit upload canvas image to NodeJS

I am trying to upload a cropped image with the Cropit jQuery plugin which uses the canvas in the front end. Basically trying to recreate process described here:

How to crop and upload photo using cropit jquery plugin with php

My Node.js effort:

var img = //DATA RECEIVED FROM THE POST REQUEST
var decoded = decodeURIComponent(require('url').parse(img, true).path.replace(/\++/g, ' '))
var exp = decoded.replace('data:image/jpeg;base64','').split(',');
var base64 = exp.shift();
var data = base64url.decode(base64);
fs.writeFile('./public/woooo.jpg', data,function(err,done){
   if (err){
     console.log(err)
   }
})

The result is an image file which cannot be opened. Why? What am I doing wrong? Anyone else has managed this?