A vanilla javascript method that returns the closest DOM ancestor that matches a selector, or null.

closest.js

var closest = function(selector, ele) {
	if(!selector || !ele) return null;

	//polyfill .matches()
	if(Element && !Element.prototype.matches) {
		Element.prototype.matches = Element.prototype.matchesSelector || Element.prototype.mozMatchesSelector || Element.prototype.msMatchesSelector || Element.prototype.oMatchesSelector || Element.prototype.webkitMatchesSelector;
	}

	if(ele.matches(selector)) return ele; //return self if it matches

	var parent = ele.parentNode;
	var i = 0;

	while(!parent.matches(selector)) {
		parent = parent.parentNode;
		if(parent.tagName == undefined) return null; //reached the end of the DOM tree
		if(i >= 100) return null; //emergency break
		i += 1;
	}

	return parent;
}

I guess I'll use this until there is consistent browser support for the native closest() function cough IE, Edge