[Dilettante_Pro]

Вариант

var arrOne = [0, 9, 10, 11, 12, 20, 28, 32, 33, 47, 65, 69],
     arrTwo = [8, 14, 15, 16, 17, 18, 19, 31, 35, 36, 37, 58, 68, 73],
     i = 0, j = 0;
while (i < arrOne.length) {
   if(arrOne[i] < arrTwo[j]) {
      while(arrOne[i + 1] < arrTwo[j]) { arrOne.splice(i, 1);}
      i++; j++;
   } else {
       arrTwo.splice(j, 1);
   }
}
alert(arrOne + '\n' + arrTwo);