Нахождение ячейки в таблице

let table = document.getElementById('my-table'); 
 
let findingInTable = function(row, cell) { 
  return table.getElementsByTagName('tr')[row].getElementsByTagName('td')[cell].innerHTML; 
} 
 
let findingInTableES6 = (row, cell) => table.getElementsByTagName('tr')[row].getElementsByTagName('td')[cell].innerHTML; 
 
console.log(findingInTable(2, 1)); 
console.log(findingInTableES6(1, 2)); 
 
 
let findingInTableJQ = (row, cell) => $('table#my-table tr:nth-child(' + row + ') td:nth-child(' + cell + ')').html(); 
 
console.log(findingInTableJQ(1, 2));

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
<table id="my-table"> 
  <tr> 
    <td>1</td> 
    <td>2</td> 
    <td>3</td> 
  </tr> 
  <tr> 
    <td>4</td> 
    <td>5</td> 
    <td>6</td> 
  </tr> 
  <tr> 
    <td>7</td> 
    <td>8</td> 
    <td>9</td> 
  </tr> 
</table>

function getCell(x,y){ 
  var cell = $('table').find('tr').eq(y-1).children('td').eq(x-1); 
  return cell; 
} 
$('button').click(function(){ 
  $('td').removeClass('active'); 
  var x = +$('[name=column]').val(); 
  var y = +$('[name=row]').val(); 
  getCell(x,y).addClass('active'); 
})

table{ 
  border-collapse:collapse; 
} 
td{ 
  padding:3px; 
  border:1px solid; 
  transition:all .2s ease; 
} 
td.active{ 
  background-color:rgba(255,0,0,.3); 
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
<table> 
  <tr> 
    <td>1</td> 
    <td>2</td> 
    <td>3</td> 
  </tr> 
  <tr> 
    <td>4</td> 
    <td>5</td> 
    <td>6</td> 
  </tr> 
  <tr> 
    <td>7</td> 
    <td>8</td> 
    <td>9</td> 
  </tr> 
</table>  
<input type="number" min="1" max="3" name="row" placeholder="Ряд" /> 
<input type="number" min="1" max="3" name="column" placeholder="Колонка" /> 
<button>Обозначить ячейку</button>