JSFiddle - React, Tailwind, and code Playground

HTML

<body>


</body>

CSS

.cell {
  width: 31px;
  height: 31px;
  border: 1px solid blue;
}

JavaScript

var grid = document.createElement('table');
    
    var row = 15;
    var column = 15;
 
    var mousedown = false;
    var selected = false;

    for(i = 1; i <= row; i++){
      var tr = document.createElement('tr');
      for(j = 1; j <= column; j++){
        var td = document.createElement('td');
        td.className = 'cell';
        tr.appendChild(td);
      }
      grid.appendChild(tr);
    }
    document.body.appendChild(grid);