function buildTable() {
  var table = {}
  keyboard = [
    "qwertyuiop".split(''),
    "asdfghjkl".split(''),
    "zxcvbnm".split(''),
  ]
  for (var row = 0; row < keyboard.length; row++) {
    for (var col = 0; col < keyboard[row].length; col++) {
        table[keyboard[row][col]] = row;
    }
  }
  return table;
};

function valid(table, chars) {
  for (var i = 1; i < chars.length; i++){
    if (table[chars[i]] != table[chars[i-1]]) {
      return false;
    }
  }
  return true;
};

table = buildTable();
console.log(table);

const inputs = ['Alaska', 'Dad', 'apple']
for (var i = 0; i < inputs.length; i++) {
  if (valid(table, inputs[i].toLowerCase())) {
    console.log('[VALID ROW] ' + inputs[i]);
  }
}