<?php
    if(isset($_POST['yazilan'])) {
        echo $_POST['yazilan'];
        exit();
    }
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" dir="ltr" lang="tr">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
        <meta http-equiv="content-language" content="TR"/>
        <script src="//code.jquery.com/jquery-1.10.2.js"></script>
    </head>
    <body>
        <form id="formum">
            <input type="text" name="yazilan" id="yazdigim" value="test"/>
            <input type="button" onclick="formsubmit();" value="Gönder"/>
        </form>
    </body>
    <script type="text/javascript">
        $("#yazdigim").change(function(){
            var yazdigim = $(this).val();
            if(yazdigim.length > 0) {
                formsubmit();
            }
        });
        function formsubmit() {
            $.ajax({
                url : "islem.php",
                type: "POST",
                data : $("#formum").serialize(),
                success: function(data)
                {
                    window.alert(data);
                }
            });
        }
    </script>
</html>
son yorumları görmemişim konuyu da yanlış anlamışım sanırım her neyse belki başkasının ihtiyacı olur