HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>matches MDN birds</title>
</head>
<body>
  <ul id="birds">
    <li>Orange-winged parrot</li>
    <li class="endangered">Philippine eagle</li>
    <li>Great white pelican</li>
  </ul>
  <button type="button" id="btn">Check birds</button>
  <pre id="out">—</pre>
  <script>
    document.getElementById("btn").onclick = function () {
      var lines = [];
      var birds = document.querySelectorAll("#birds li");
      for (var i = 0; i < birds.length; i++) {
        var bird = birds[i];
        if (bird.matches(".endangered")) {
          lines.push("The " + bird.textContent + " is endangered!");
        }
      }
      document.getElementById("out").textContent = lines.join("\n") || "No endangered birds";
    };
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

Element.matches — MDN endangered birds (Try It)