    <!DOCTYPE html>
    <html>
    <head>
      <meta charset="UTF-8">
      <title>전역객체 메서드 사용하기</title>
      <link rel="stylesheet" href="style_js.css">
    <body>
      <script>
        const jud = window.confirm("confirm()에서 window.가 생략된 것을 이해했나요?");
        document.write("전역객체 속성 이해했음:  " + jud + "<hr>");
        document.write("isNaN(1) = " + isNaN(1) + "<hr>");
        document.write("isNaN('0.5') = " + isNaN('0.5') + "<hr>");
        document.write("isNaN('str') = " + isNaN('str') + "<hr>");
        document.write("eval(3 * 4) = " + eval(3 * 4));
      </script>
    </body>
    </html>