js_io.js

<script src="http://code.jquery.com/jquery-2.1.3.min.js"></script> 
<script type="text/javascript">
$(document).ready(function(){
            $("#submit").click(function(){
                var postInputVal = $("#postinput").val();
                $("#postecho").val(postInputVal);
                console.log("OK!");
            });
        });
    </script>