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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>createExpression MDN</title>
  <style>body{font-family:system-ui,sans-serif;padding:1.5rem;} nav,section{border:1px solid #ccc;padding:0.75rem;margin:0.5rem 0;} pre{border:1px solid #ccc;padding:0.75rem;}</style>
</head>
<body>
  <nav><div>In nav</div></nav>
  <section><div>Outside nav</div></section>
  <button id="btn" type="button">Compile and evaluate //div</button>
  <pre id="out">Click the button</pre>
  <script>
    function countNodes(result) {
      var n = 0;
      var node = result.iterateNext();
      while (node) { n++; node = result.iterateNext(); }
      return n;
    }
    document.getElementById("btn").addEventListener("click", function () {
      var xpathExpr = document.createExpression("//div");
      var all = xpathExpr.evaluate(document, XPathResult.ORDERED_NODE_ITERATOR_TYPE);
      var nav = document.querySelector("nav");
      var scoped = xpathExpr.evaluate(nav, XPathResult.ORDERED_NODE_ITERATOR_TYPE);
      document.getElementById("out").textContent = [
        "XPathExpression: " + (xpathExpr instanceof XPathExpression),
        "//div on document: " + countNodes(all),
        "//div on nav: " + countNodes(scoped)
      ].join("\n");
    });
  </script>
</body>
</html>

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