Element.matches()

matches(selectors)

<ul id="birds">
  <li>Orange-winged parrot</li>
  <li class="endangered">Philippine eagle</li>
  <li>Great white pelican</li>
</ul>

<script type="text/javascript">
  var birds = document.getElementsByTagName("li");

  for (var i = 0; i < birds.length; i++) {
    if (birds[i].matches(".endangered")) {
      console.log("The " + birds[i].textContent + " is endangered!");
    }
  }
</script>

<div id="foo">This is the element!</div>
  <script type="text/javascript">
    var el = document.getElementById("foo");
    if (el.mozMatchesSelector("div")) {
      alert("Match!");
    }
  </script>

if (!Element.prototype.matches) {
  Element.prototype.matches =
    Element.prototype.matchesSelector ||
    Element.prototype.mozMatchesSelector ||
    Element.prototype.msMatchesSelector ||
    Element.prototype.oMatchesSelector ||
    Element.prototype.webkitMatchesSelector ||
    function (s) {
      var matches = (this.document || this.ownerDocument).querySelectorAll(s),
        i = matches.length;
      while (--i >= 0 && matches.item(i) !== this) {}
      return i > -1;
    };
}