Show output value in input box using javascript, html and php

Following below code output value input text box using ajx, php

<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script>
function get_id_val(val){  
    var option = val.options[val.selectedIndex];
    var hr = new XMLHttpRequest();
    $.ajax({
        type: "GET",
        url: "sql.php",
        data: "value="+option.value,
        success: function(message){
        //    alert(message);
        //$("#result").html(message);
        //   $('#s_op_id').val(message.s_op_id);
        //$("#s_op_id").val(message.returnValue);  
        // body:$('#s_op_id').val()
        // alert(data);
        //          $('#s_op_id').text(data);
        // $('#s_op_id').val(data);
        // document.form1.s_op_id.value = $('#s_op_id').val();

        // var return_data = message;
        // alert(return_data);
        //document.getElementById("s_op_id").innerHTML = message;
  document.form1.s_op_id.value = message;           

        },
            failure: function() {
                alert('fail');
            }
       
    });

}
  
           
</script>

<form name="form1" >
<select onchange="javascript:get_id_val(this)" id="variation_select_61_10" class="wpsc_select_variation">
    <option value="0" disabled="disabled">-- Please Select --</option>
    <option value="13">L</option>
    <option value="12">M</option>
    <option value="11">S</option>
</select>

<input type="text" name="s_op_id" id="s_op_id"/>

<!-- <div  id="result">
*/result shows here /*
</div> --></form>

php code as file sql.php

<?php
echo $_REQUEST['value'];

?>