Update: Now supported in most major browsers
document.querySelector("p").closest(".near.ancestor")
Note that this can match selectors, not just classes
https://developer.mozilla.org/en-US/docs/Web/API/Element.closest
For legacy browsers that do not support closest()
but have matches()
one can build selector-matching similar to @rvighne’s class matching:
function findAncestor (el, sel) {
while ((el = el.parentElement) && !((el.matches || el.matchesSelector).call(el,sel)));
return el;
}