Mail Delete Button

<html>
<head>
<title>http://stackoverflow.com/questions/11335649/show-hide-div-when-checkbox-is-selected</title>
<script type='text/javascript'>
<!--

function updateMDBstatus() {
    var f = document.messageform;
    var c = f.getElementsByTagName('input'); //collection
    for (var i=0; i < c.length; i++) {
        if (c[i].type && c[i].type == 'checkbox' && c[i].checked == true) {
            document.getElementById('mail_delete_button').style.display = "block";
            return;
        }
    }
    document.getElementById('mail_delete_button').style.display = "none";
}
function initCheckboxes() {
    var f = document.messageform;
    var c = f.getElementsByTagName('input'); //collection
    for (var i=0; i < c.length; i++) {
        if (c[i].type && c[i].type == 'checkbox') {
            if (c[i].addEventListener) {
                c[i].addEventListener('change',updateMDBstatus,false);
            } else if (pic.attachEvent) {
                c[i].attachEvent('onchange',updateMDBstatus);
            }
        }
    }
}

window.onload = initCheckboxes; // see also http://www.webreference.com/programming/javascript/onloads/
//-->
</script>

</head>

<body>

<form name="messageform">
<input type="checkbox" name="delete_convos[]" value="1"> <input type="text" name="aaa[]" value="1"> <br/>
<input type="checkbox" name="delete_convos[]" value="2"> <input type="text" name="aaa[]" value="2"> <br/>
<input type="checkbox" name="delete_convos[]" value="3"> <input type="text" name="aaa[]" value="3"> <br/>
</form>

<div id="mail_delete_button" style="display:none"> DIV : Mail Delete Button </div>

</body>
</html>