I've never been the best with Regex, but here's a possible attempt:
const acceptableSequence = str => !/(?<!\+)\w|\w(?!\+)/.test(str);
EDIT: Misread the requirements, don't need to account for end and beginning of line characters as exceptions.
\w generally includes the underscore, which is why I used the explicit character class.
That's a good point. I figured I'd use \w since nothing in the challenge indicated that the characters need be only alphabetical, but obviously you could just as easily sub in [a-zA-Z] or whatever fits the use case.
I interpreted “The string will be composed of + and = symbols with several characters between them.” as only +, = and letters. 😀
That definitely makes the most sense, given the examples. I really appreciate you reaching out to clarify - definitely want to make sure I'm accurately hitting objectives.
I'm just assuming either, but at least this is turning into a good lesson on how requirements get confused between whoever plans them and developers 😉
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