extension method

String extension (String path)

Gets the file extension of path: the portion of basename from the last . to the end (including the . itself).

context.extension('path/to/foo.dart'); // -> '.dart'
context.extension('path/to/foo'); // -> ''
context.extension('path.to/foo'); // -> ''
context.extension('path/to/foo.dart.js'); // -> '.js'

If the file name starts with a ., then it is not considered an extension:

context.extension('~/.bashrc');    // -> ''
context.extension('~/.notes.txt'); // -> '.txt'

Implementation 

String extension(String path) => _parse(path).extension;