JSFiddle - React, Tailwind, and code Playground by Emily Humphrey June 24, 2015 HTML <a href="mailto:[email protected]">Should not be red</a> <a href="http://reddittest.com">Should be red</a> <a href="http://fiddle.jshell.net/">Should not be red</a> CSS body{ padding: 0; margin: 0; font-family: sans-serif; } a{ display: block; padding: 2px; margin: 2px; text-decoration: none; color: blue; } a[target="_blank"]{ color: red } JavaScript $('a').each(function() { var link = new RegExp("/"+window.location.host+"/"); if(!link.test(this.href)){ if(this.href.substring(0, 7) != "mailto:"){ $(this).attr("target", "_blank"); } } });