I want to toggle two elements making one display none and the other display block. And by clicking again switch the displays:

<script type="text/javascript" language="javascript1.3">
function toggle(id){
regid = "regid_" + id;
img = "img_" + id;
forumid = "forumid_" + id;
divElement = document.getElementById(regid);
imgElement = document.getElementById(img);
forumElement = document.getElementById(forumid);
if (divElement){
if (divElement.className == 'closed'){
divElement.className = "open";
forumElement.classname = "closed";
imgElement.src = "includefiles/images/opened.gif";
}else{
divElement.className = "closed";
forumElement.classname = "open";
imgElement.src = "includefiles/images/closed.gif";
}
}
}
/*function toggle(id) {
var el = document.getElementById("regid_" + id);
if ( div.style.display = 'block' ) {
div.style.display = 'none';
}
else {
div.style.display = 'block';
}
}*/
</script>
<style type="text/css">
.open {
display: block;
}
.closed {
display: none;
}
</style>
<table class="" id="" border="1" style="border: 1px;">
<tr>
<td id="tdid_0">
<div id="regid_0" class="closed" style="display: block;"><a onclick="toggle('item0');"><img src="includefiles/images/closed.gif" id="img_item0" alt="Click to Expand" border="0" /></a>blablah</div><br />

<div id="forumid_0" class="open" style="display: none;">gagah googoooh</div><br /></td>

</tr>