javascript get file extension
var fileName = "myDocument.pdf"; var fileExtension = fileName.split('.').pop(); //"pdf"
javascript get file extension from string
// 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);
Source: stackoverflow.com
JavaScript - How to get the extension of a filename
let filename = "index.js"; let extension = filename.split(".").pop(); console.log(extension); // "js"
Source: sebhastian.com