Не вижу проблемы, кажется, ваш код работает
function myFunction() {
var input, filter, table, tr, td, i, txtValue;
input = document.getElementById("myInput");
//filter = input.value.toUpperCase();
filter = '1'
table = document.getElementById("myTable");
tr = table.getElementsByTagName("tr");
for (i = 0; i < tr.length; i++) {
td = tr[i].getElementsByTagName("td")[0];
if (td) {
txtValue = td.textContent || td.innerText;
if (txtValue.toUpperCase().indexOf(filter) > -1) {
tr[i].style.display = "";
}
else {
tr[i].style.display = "none";
}
}
}
}
setTimeout(myFunction, 1000)
<table id="myTable">
<tr>
<td>1</td>
<td>2</td>
</tr>
<tr>
<td>11</td>
<td>33</td>
</tr>
<tr>
<td>2</td>
<td>2</td>
</tr>
<tr>
<td>3</td>
<td>4</td>
</tr>
<tr>
<td>3</td>
<td>5</td>
</tr>
</table>