lib/utils.js
function hasMatchingExtname(pathname, exts) {
  var suffix = path.extname(pathname).slice(1);
  return exts.some(function(element) {
    return suffix === element;
  });
}
function hasMatchingExtname(pathname, exts) {
  var suffix = path.extname(pathname).slice(1);
  return exts.some(function(element) {
    return suffix === element;
  });
}
function hasMatchingExtname ( pathname , exts ) { var suffix = path . extname ( pathname ) . slice ( 1 ) ; return exts . some ( function ( element ) { return suffix === element ; } ) ; }
Determines if pathname has a matching file extension.

@private
@param {string} pathname - Pathname to check for match.
@param {string[]} exts - List of file extensions (sans period).
@return {boolean} whether file extension matches.
@example
hasMatchingExtname('foo.html', ['js', 'css']); // => false
Determines if pathname has a matching file extension .