How to get a extension of a file using jquery or javascript? [duplicate]

Answer 1

If you need to validate multiple extensions:

var filename = "picture.jpg";
var valid_extensions = /(\.jpg|\.jpeg|\.gif)$/i;   
if(valid_extensions.test(filename))
{ 
   alert('OK');
}
else
{
   alert('Invalid File');
}

This eliminates the need to parse the string if you want to check the extension, for example, before uploading a file.