JSFiddle - React, Tailwind, and code Playground

HTML

<table>
<tbody id='moron'>
    <tr>
        <th>1x1</th>
        <th>1x2</th>
        <th rowspan="6">1x3</th>
        <th>1x4</th>
    </tr>
    <tr>
        <th colspan="2">2x1</th>
        <th>2x4</th>
    </tr>
    <tr>
        <th>3x1</th>
        <th>3x2</th>
        <th rowspan="3">3x4</th>
    </tr>
    <tr>
        <th>4x1</th>
        <th>4x2</th>
    </tr>
    <tr>
        <th>5x1</th>
        <th>5x2</th>
    </tr>
    <tr>
        <th colspan="2">6x1</th>
        <th>6x4</th>
    </tr>
</tbody>
</table>
<input type="text" id="x" value="х координата"><input type="text" id="y" value="y координата">
<div id='colored'>ПОКРАСИТЬ!</div>

CSS

table{
 border-collapse: collapse;
}
th{
 width: 50px; height: 25px;
 border: 1px solid black;
}
#colored{
 color: white;   
 background: red;
}

JavaScript

function CoordObject(idTable){
    this.table = document.getElementById(idTable);
    for(var i1=0;i1<this.table.children.length; i1++){
      var tr = this.table.children[i1];
      for(var i2=0;i2<tr.children.length; i2++){
          var i4 = i2;
          var that = this;
         if(tr.children[i2].hasAttribute('rowspan') == true){
          check();          
          var rowspan = tr.children[i2].getAttribute('rowspan');
          for(var i3=0;i3<rowspan; i3++){
            this[(i1+i3+1)+'x'+(i4+1)] = tr.children[i2];
          }
         }
         if(tr.children[i2].hasAttribute('colspan') == true){
           var colspan = tr.children[i2].getAttribute('colspan');
           for(var i3=0; i3<colspan; i3++){
             this[(i1+1)+'x'+(i2+i3+1)] = tr.children[i2];
           }
         }
         if(tr.children[i2].hasAttribute('colspan') != true && tr.children[i2].hasAttribute('rowspan') != true){
          check();
        }
        function check(){
          if((i1+1)+'x'+(i4+1) in that){
            i4++;
            check();
          }else{
            that[(i1+1)+'x'+(i4+1)] = tr.children[i2];
          }
        }
      }
    }
}
var myObj = new CoordObject('moron');
document.getElementById('colored').onclick = function(){
var x = document.getElementById('x').value;
var y = document.getElementById('y').value;
myObj[x+'x'+y].style.background = 'red';
}