The way you're doing it now, it's looking for the whole string as is, literally, not interpreting the ||
as any form of or
.
You can either set the element in the switch to uppercase or lowercase use :
switch(month.toLowerCase()) {
case "january" :
...
break;
case "february":
...
...
}
or you have to double case elements:
switch (month) {
case "January":
case "january":
...
break;
case "February":
case "february":
...
...
}