Взять десять минут ходьбы JS

function isValidWalk(walk) {
  var dx = 0
  var dy = 0
  var dt = walk.length

  for (var i = 0; i < walk.length; i++) {
    switch (walk[i]) {
      case 'n': dy--; break
      case 's': dy++; break
      case 'w': dx--; break
      case 'e': dx++; break
    }
  }

  return dt === 10 && dx === 0 && dy === 0
}
Evil Elephant