var mergeArr = (...args) => {
  var tmp_1 = []
  var tmp_2 = [''];
  var i = 0;
  args.forEach((arr) => {
    j = 0;
    arr.forEach((x) => {
      if(i % 2) {
        tmp_1.forEach((y) => {
          tmp_2[j] = y + x;
          j++;
        });
      } else {
        tmp_2.forEach((y) => {
          tmp_1[j] = y + x;
          j++;
        });
      }
    });
    i++;
  });
  if(i % 2) {
    //console.log(tmp_1);
  } else {
    //console.log(tmp_2);
  }
}