Test if links are external with jQuery / javascript?

Question

How do I test to see if links are external or internal? Please note:

1. I cannot hard code the local domain.
2. I cannot test for \"http\". I could just as

Answer 1

I use this function for jQuery:

$.fn.isExternal = function() {
  var host = window.location.host;
  var link = $('', {
    href: this.attr('href')
  })[0].hostname;
  return (link !== host);
};

Usage is: $('a').isExternal();

Example: https://codepen.io/allurewebsolutions/pen/ygJPgV