Complete Form Validation JavaScript Part 3

<style type="text/css">
    #form{
        margin-top:100px;
        margin-left:30px;
    }
    .warning_msg{
        color:#ae0000;
        margin:3px 0px 0px 5px
    }
    .warning_brd{
        border:1px solid #ae0000
    }
</style>


<script type="text/javascript">
    //function displays the error message
    function displayWarning(field_id, parent_div, message){
        var para = document.createElement("p");
        para.setAttribute("class","warning_msg");
        var error_msg = document.createTextNode(message);
        para.appendChild(error_msg);
        document.getElementById(parent_div).appendChild(para);
        document.getElementById(field_id).className += " warning_brd";
    }
</script>