HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>createTreeWalker filter</title>
  <style>body{font-family:system-ui,sans-serif;padding:1.5rem;} pre{border:1px solid #ccc;padding:0.75rem;}</style>
</head>
<body>
  <div id="box">
    <div class="keep" id="a">A</div>
    <div class="skip-branch">
      <div class="keep" id="b">B (hidden by REJECT)</div>
    </div>
    <div>
      <div class="keep" id="c">C</div>
    </div>
  </div>
  <button id="btn" type="button">Run filter walk</button>
  <pre id="out">Click the button</pre>
  <script>
    document.getElementById("btn").addEventListener("click", function () {
      var walker = document.createTreeWalker(
        document.querySelector("#box"),
        NodeFilter.SHOW_ELEMENT,
        function (node) {
          if (node.classList.contains("skip-branch")) {
            return NodeFilter.FILTER_REJECT;
          }
          if (node.classList.contains("keep")) {
            return NodeFilter.FILTER_ACCEPT;
          }
          return NodeFilter.FILTER_SKIP;
        }
      );
      var kept = [];
      while (walker.nextNode()) {
        kept.push(walker.currentNode.id || walker.currentNode.tagName);
      }
      document.getElementById("out").textContent = kept.join(", ");
    });
  </script>
</body>
</html>

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Document.createTreeWalker — custom filter (Try It)