function buildTable() {
  var table = {}
  const rowA = "qwertyuiop".split('')
  const rowB = "asdfghjkl".split('')
  const rowC = "zxcvbnm".split('')

  for (var i = 0; i < rowA.length; i++) {
    table[rowA[i]] = 1;
  }
  for (var i = 0; i < rowB.length; i++) {
    table[rowB[i]] = 2;
  }
  for (var i = 0; i < rowC.length; i++) {
    table[rowC[i]] = 3;
  }
  return table;
};

function valid(table, chars) {
  ret = []
  for (var i = 0; i < chars.length; i++) {
    ret.push(table[chars[i]]);
  }
  console.log('[DEBUG] ' + chars + ' => ' + ret)
  for (var i = 1; i < ret.length; i++){
    if (ret[i] != ret[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]);
  }
}