Warn about confusing quantifiers.
configuration in plugin:clean-regex/recommended: "warn"
Confusing quantifiers are ones which imply one thing but don't deliver on that.
An example of this is (?:a?b*|c+){4}. The group is quantified with {4} which
implies that at least 4 characters will be matched but this is not the case. The
whole pattern will match the empty string. It does that because in the a?b*
alternative, it's possible to choose 0 many a and b. So rather than {4},
{0,4} should be used to reflect the fact that the empty string can be matched.
Examples of valid code for this rule:
/a*/
/(a|b|c)+/
/a?/Examples of invalid code for this rule:
/(a?){4}/ // warns about `{4}`
/(a?b*)+/ // warns about `+`