Fastest way to detect external URLs

Question

What\'s the fastest method to detect if foo=\'http://john.doe\' is an external url (in comparsion to window.location.href)?

Answer 1

The main problem, is how to parse an URL, and get a host name our of it. It can be done with following way:

var _getHostname = function(url) {
  var parser = document.createElement('a');
  parser.href = url;

  return parser.hostname;
}

var isExternal = (_getHostname(window.location.href) !== _getHostname('http://john.doe'));

Or you can use is-url-external module.

var isExternal = require('is-url-external');
isExternal('http://john.doe'); // true | false