Open external links in a new tab without jQuery

Question

What's the best way to open all external links (URLs that don't match the current domain) in a new tab using JavaScript, without using jQuery?

Here's the jQuery I'm current using:

// Open external links in new tab
$('a[href^=http]').click(function () {
    var a = new RegExp('/' + window.location.host + '/');
    if (!a.test(this.href)) {
        window.open(this.href);
        return false;
    }
});

Answer 1

Pure JS:

function externalLinks() {
  for(var c = document.getElementsByTagName("a"), a = 0;a < c.length;a++) {
    var b = c[a];
    b.getAttribute("href") && b.hostname !== location.hostname && (b.target = "_blank")
  }
}
;
externalLinks();