If checkbox has certain value, show div

I want javascript to check to see if a checkbox is marked as a certain value; if it does, a div would display as "block". If not, it would display as "hidden". In this example,"oForm" is the form name,  "alumn" is the div that is shown or hidden, "affiliation" is the input (checkbox), and it's marked [0] because it's the first of six boxes with "affiliation" as the value.

So, here's the script that doesn't work:

<script language="javascript">
function checkAlumni() {
  document.getElementById("alumn").style.display = (document.oForm.affiliation[0].checked)?"block":"none";
}
</script>

And here's the call:

<body onload="checkAlumni()">

Any thoughts as to what's going wrong? Thanks!
sholmstedtAsked:
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Yury MerezhkovDevelopment Team LeadCommented:
Change your function to this:

function checkAlumni() {
   document.getElementById("alumn").style.display =    document.oForm.affiliation.checked)?"block":"none";
}
0
Yury MerezhkovDevelopment Team LeadCommented:
This I mean:

      function checkAlumni() {
            document.getElementById("alumn").style.display = (document.oForm.affiliation.checked)?"block":"none";
      }
0

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Yury MerezhkovDevelopment Team LeadCommented:
You don't need that [0] after affiliation.
0
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b0lsc0ttIT ManagerCommented:
Let's see the html for the form and checkbox.  Also, the html for the element with the id "alumn".  You can put an alert in that function but I think it is getting called.  The problem is probably somewhere else.

I normally recommend you "show" something by just deleting the none value.  For example ...

  document.getElementById("alumn").style.display = (document.oForm.affiliation[0].checked)? "":"none";

Are you getting a javascript error?  Is the div being hidden, shown or neither (i.e. depending on checkbox)?  Let me know if you have a question or need more information.

bol
0
Sudaraka WijesingheWeb Application ProgrammerCommented:
try changing oForm to forms[0] on your JavaScript statement.

<html>
<head>
<script language="javascript" type="text/javascript">
function checkAlumni() {
  document.getElementById("alumn").style.display = (document.forms[0].affiliation[0].checked)?"block":"none";
}
</script>
</head>
<body onload="checkAlumni()">
      <form id="oForm">
            <input type="checkbox" id="affiliation" checked="checked" /> affiliation 1<br />
            <input type="checkbox" id="affiliation" /> affiliation 2<br />
            <input type="checkbox" id="affiliation" /> affiliation 3<br />
            <input type="checkbox" id="affiliation" /> affiliation 4<br />
            <input type="checkbox" id="affiliation" /> affiliation 5<br />
            <input type="checkbox" id="affiliation" /> affiliation 6<br />
      </form>
      <div id="alumn">
            content of alumn
      </div>
</body>
</html>

Worked for me on both IE7 and FF2

document.getElementById("oForm") will also work (my favorite)
  document.getElementById("alumn").style.display = (document.getElementById("oForm").affiliation[0].checked)?"block":"none";

Hope this helps
0
vjc2003Commented:
script looks OK.
you may  need to call checkAlumni() on onpropertychange of checkbox
if you want to switch visibility when you check or uncheck.
0
vjc2003Commented:
script looks OK.
you may  need to call checkAlumni() on onpropertychange of checkbox
if you want to switch visibility when you check or uncheck.
0
sholmstedtAuthor Commented:
Sorry all, I've been putting out a huge fire on another project. I will test these today. Thanks for your help.
0
b0lsc0ttIT ManagerCommented:
The onpropertchange is proprietary to IE and will have poor, if any support, in other browsers.  The onclick event is better (universally supported) if you wish to not be limited to IE.

bol
0
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