let studentsData = [['Jack', 24], ['Sara', 23],];
for (let i of studentsData) {
for (let j of i) {
console.log(j);
}
}
var squares = new Array();
for(var i = 0; i <= 8; i++)
{
squares[i] = new Array();
for(var j = (i * 20) + 1; j <= 20 * i + 20; j++)
if (squares[i] == null)
squares[i] = j;
else
squares[i].push(j);
}