HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>PIN validation</title>
</head>
<body>
  <h1>PIN validation</h1>
  <pre id="out"></pre>
  <script>
    var pinPattern = /^[0-9]{4}$/;
    function isValidPin(pin) { return pinPattern.test(pin); }
    document.getElementById("out").textContent =
      isValidPin("1234") + "\n" +
      isValidPin("12a4") + "\n" +
      isValidPin("12345");
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

JavaScript RegExp [0-9] — PIN validation (Try It)