Match One of Many Alternatives

cat|dog|bird matches one of cat, dog and bird.

The order of the alternatives in the regex matters only when two of them can match at the same position in the string.

Alternatives are short-circuited(or eager). If the previous alternative matches, the rest won't continue to match at current position.

So Jane|Janet can't match Janet in Her name is Janet, only Jane is matched. To match word by word, use \bJane\b|\bJanet\b instead.