Is there any way to make this function shorter? I want to calculate the characters up to 1.000.000.My reverse function looks like the same also...function toABC(num) {switch (num) {    case 1: return 'A';    case 2: return 'B';    case 3: return 'C';    case 4: return 'D';    case 5: return 'E';    case 6: return 'F';    case 7: return 'G';    case 8: return 'H';    case 9: return 'I';    case 10: return 'J';    case 11: return 'K';    case 12: return 'L';    case 13: return 'M';    case 14: return 'N';    case 15: return 'O';    case 16: return 'P';    case 17: return 'Q';    case 18: return 'R';    case 19: return 'S';    case 20: return 'T';    case 21: return 'U';    case 22: return 'V';    case 23: return 'W';    case 24: return 'X';    case 25: return 'Y';    case 26: return 'Z';    case 27: return 'AA';    default: return '-';}}
How to simplify this js function?
javascript