Personally, I'd prefer to go with early return, I think. Depending on what the conditions mean semantically.
It would be:
if (conditionA && conditionB) {
return "A & B"
}
if (conditionA) {
return "A"
} else {
return "Not A"
}
return "neither A nor B"
Regarding nested ternaries, while not recommended, short circuit evaluations may be even more readable:
return ( (cA && cB && "A & B") || (cA && "A") || (cB && "B") || "neither" );
Quick, it's another case of Javsacript Stockholm Syndrome!
:-)
However, this would also work in Perl, etc, (anything featuring short-circuit evaluation and type coercion for evaluating conditions.)
The 2nd one, there's a caveat about space/GC here.
The 3rd one depends a lot on the situation.
4th one is too obvious for it to be called a pattern, but I agree with it.
5th one is, meh, not really easy to read. I prefer his "bad" example. It could be less verbose, e.g,
if (!conditionA) result = "Not A"
else if (conditionB) result = "A & B"
else result = A