    <!DOCTYPE html>
    <html>
    <head>
      <meta charset="UTF-8">
      <title>윈도우 이동시키기</title>
      <link rel="stylesheet" href="style_js.css">
    </head>
    <body>
      <input type="button" value="윈도우 만들기" onclick="openWin()"><hr>
      <input type="button" value="윈도우 위로" onclick="upWin()"><br>
      <input type="button" value="윈도우 아래로" onclick="downWin()"><hr>
      <input type="button" value="윈도우 닫기" onclick="closeWin()">
      <script>
        let newWin;
        function openWin() {
            newWin = open("", "", "width=300, height=200");
            newWin.document.write("움직이는 윈도우");
            newWin.moveTo(300, 300);
        }
        function upWin() {
            newWin.moveBy(0, -10);
        }
        function downWin() {
            newWin.moveBy(0, 10);
        }
        function closeWin() {
          if (newWin)
            newWin.close();
        }
      </script>
    </body>
    </html>