var username, password;
var secUser = 'furry';
var secPass = 'yiff';
var successLevel = 0;

if(username == secUser) {
    successLevel = successLevel + 1; // we add one to our level, so the switch can know we made it to here
}

if (password = secPass) {
    successLevel = succsesLevel + 2; // we add two here just to be different from the 1
}

/* here is the switch statement:

if we only had the username correct,
then the succseslevel is 1.

if we only have the password correct,
then the successlevel is 2.

if both are correct, the level is 3.

if neither are correct the level is 0.

I put a mistake in the case structure on purpose
so that you will see why the thing I was talking
was needed

*/

switch(successLevel) {
    case 0:
        // incorrect username and password
    case 1:
        // incorrect password
        break;
    case 2:
        // incorrect username
        break;
    default:
        // incorrect username and password (this is just to catch for validity sake)
}