xxxxxxxxxx
var fileName = "myDocument.pdf";
var fileExtension = fileName.split('.').pop(); //"pdf"
xxxxxxxxxx
let filename = "index.js";
let extension = filename.split(".").pop();
console.log(extension); // "js"
xxxxxxxxxx
// 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);
xxxxxxxxxx
var fileName = "myDocument.pdf";
var fileExtension = fileName.split('.').pop(); //"pdf"