<script type="text/javascript" language="javascript">
    var xhreq = new XMLHttpRequest();
    function Button1_Click()
    {
        var uri = "http://localhost:3422/Service.asmx/ListItems?name=&code=&format=";
        var result = document.getElementById("result");
        xhreq.open("GET", uri, false);
        xhreq.send();
        result.value = xhreq.responseText;
    }
</script>