Аналогичное решение на jQuery
<!DOCTYPE html >
<html>
<head>
<title></title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script>
$(window).ready(function () {
$('#td_name').on('click', function () {
alert($(this).next().text());
});
});
</script>
</head>
<body>
<table>
<tr>
<td id="td_name" >ООО "Вега"</td>
<td style="display:none">Some Value in next cell</td>
</tr>
</table>
</body>
</html>