Untitled

<html>
    <head>
        <title>YYMMDD</title>
    </head>
    <body>
        <input id="ot1" value="170101" autofocus>
        <script>
            var date = new Date();
            var yy = ("" + date.getFullYear()).slice(-2);
            var mm = ("0" + (date.getMonth() + 1)).slice(-2);
            var dd = ("0" + date.getDate()).slice(-2);
            document.getElementById("ot1").value = yy + mm + dd;
        </script>
    </body>
</html>