body {
    font-family: Consolas, monospace;
}

table {
    border: 1px solid #111111;
}

td {
    width: 20px;
    height: 20px;
    border: 1px solid #111111;
    text-align: center;
}

const table = document.createElement('table');

for (let i = 0; i < 10; i++) {
    const row = table.insertRow();
    for (let j = 0; j < 10; j++) {
        const cell = row.insertCell();
        cell.textContent = +(i === j);
    }
}

document.body.append(table);