<html>
<head>
</head>
<body>
<table>
<tr><td>111<td>111<td>111
<tr><td>111<td>111<td>111
<tr><td>111<td>111<td>111
</table>
<script>
document.querySelectorAll('td').forEach(el => el.onclick = e => el.style.backgroundColor = 'red');
</script>
</body>
</html>