Javascript Map Array Last Item

Try something like:

row.map((rank, i, row) => {
  if (i + 1 === row.length) {
    // Last one.
  } else {
    // Not last one.
  }
})

Old answer:

const rowLen = row.length;
row.map((rank, i) => {
  if (rowLen === i + 1) {
    // last one
  } else {
    // not last one
  }
})