//add rel=noopener to any target=_blank links
(function(){

	//minimum requirements... if a browser is old enough not to
	//handle these, window.opener is the least of its worries
	if(	!('querySelector' in document && 'querySelectorAll' in document) ||
		!('addEventListener' in window) ||
		!('opener' in window)
	)
		return;



	//detect potentially dangerous targets
	var badTarget = function(target){
		return (!target || ['_self', '_top', '_parent'].indexOf(target) === -1);
	};



	//detect potentially dangerous destinations
	var badDestination = function(href){
		return (href && !/^\#/.test(href));
	};



	//add/update rel=noopener
	var updateLinks = function(){
		var links = document.querySelectorAll('a[target=_blank]');
		if(links.length){
			for(i=0; i<links.length; i++){
				var rel = [],
					link = links[i],
					target = link.getAttribute('target') || false,
					href = link.getAttribute('href') || false;

				//we only need to worry about certain links
				if(badDestination(href) && badTarget(target)){
					//parse existing rels
					if(links[i].hasAttribute('rel'))
						rel = links[i].getAttribute('rel').split(' ');

					//add noopener if necessary
					if(['noopener','noreferrer'].indexOf(rel) === -1){
						rel.push('noopener');
						links[i].setAttribute('rel', rel.join(' '));
					}
				}
			}
		}
	};



	//trigger on DOMReady
	document.addEventListener('DOMContentLoaded', function(){ updateLinks(); });
})();