table generator

table.js

const app = document.querySelector('#app')
const columns = 10;
const rows = 10;
const table = document.createElement('table');
table.border=1;
for (var i = 0; i < rows; i++) {
  const tr = document.createElement('tr')
  for (var j = 0; j < columns; j++) {
    const td = document.createElement('td')
    td.textContent = j == 0 ? i : j;
    td.onclick = selectTd;
    tr.append(td)
  }
  table.append(tr)
}
app.append(table)
function selectTd() {
  this.style.background = 'red'
}