1function diamond(val) {
2  let y,
3    w,
4    shape = '';
5
6  for (y = 0; y < val * 2 - 1; y++) {
7    w = y < val ? y : val * 2 - y - 2;
8    shape += Array(val - w).join(' ') + Array(w + 1).join('* ') + '*\n';
9  }
10  console.log(shape);
11}
12
13diamond(4);