var ext = fileName.split('.').pop();
var ext = fileName.substr(fileName.lastIndexOf('.') + 1);
let filename = "index.js";
let extension = filename.split(".").pop();
console.log(extension); // "js"
// Use the lastIndexOf method to find the last period in the string, and get the part of the string after that:
var ext = fileName.substr(fileName.lastIndexOf('.') + 1);
return filename.split('.').pop();
var fileName = "myDocument.pdf";
var fileExtension = fileName.split('.').pop(); //"pdf"
const path = require('path')
path.extname('picture.png') //.png
path.extname('picture.of.a.dog.png') //.png
path.extname('picture.of.a.dog.jpg') //.jpg
path.extname('picture.of.a.dog.jpeg') //.jpeg
file.originalname.match(/..*$/)[0]