<body>
<div id="target">
<div class="a">
</div>
<div class="b">
</div>
<div class="c">
</div>
</div>
<script type="text/javascript">
var elements = document.getElementById('target').getElementsByTagName('*');
for (var i = 0; i < elements.length; i++) {
alert(elements[i].getAttribute('class'));
}
</script>
</body>
<body>
<div id="target">
<div class="a">
</div>
<div class="b">
</div>
<div class="c">
</div>
</div>
<script type="text/javascript">
var elements = document.getElementById('target').getElementsByTagName('*');
for (var i = 0; i < elements.length; i++) {
elements[i].setAttribute('class','class'+i)
alert(elements[i].getAttribute('class'));
}
</script>
</body>