how to get file extension in javascript

1var fileName = "myDocument.pdf";
2var fileExtension = fileName.split('.').pop(); //"pdf"

1var ext =  fileName.split('.').pop();

1var ext = fileName.substr(fileName.lastIndexOf('.') + 1);

1return filename.split('.').pop();
2

1// Use the lastIndexOf method to find the last period in the string, and get the part of the string after that:
2
3var ext = fileName.substr(fileName.lastIndexOf('.') + 1);
4

1var fileName = "myDocument.pdf";
2var fileExtension = fileName.split('.').pop(); //"pdf"