External Link Warning

HTML

<a href="https://www.fiddle.jshell.net/test.html">Absolute Local Link</a><br>
<a href="/test.html">Relative Local Link</a><br>
(these local links don't go to real pages, FYI)
<br>
<a href="mailto:[email protected]">Mailto Link</a>
<hr>
<a href="https://www.google.com">External Link</a>

JavaScript

/* EXTERNAL LINK WARNING
=========================================*/
$('a').on('click', function(e){
	e.preventDefault();
	var url = $(this).attr('href'),
		host = location.host;		
	if (url.indexOf(host) > -1 || url.indexOf('http','https') == -1){
		/* If we find the host name within the URL,
			   OR if we do not find http or https, 
			   meaning it is a relative internal link
			*/
		window.location.href = url;
	} else {
		var warn = confirm('You\'re leaving the domain.\n\nAre you sure?');
		if(warn == true) {
			window.location.href = url,'_blank';
		} else {
			e.preventDefault;
		}
	}
});