Lack of essential detail about regexp lookbehind syntax in "Lookahead and lookbehind" article

Part 3 (Additional articles)
Chapter 7 (Regular expressions)
Article 14 (Lookahead and lookbehind)

Why you don't mention that in JS non fixed length regexps (including quantifiers, backreferences etc.) are not allowed inside lookbehind expression ?

First you talk about lookahead, and using regexp with quantifier as lookahead condition in your example.

Copied from www.javascript.info
For example, \d+(?=\s)(?=.*30) looks for \d+ that is followed by a space (?=\s), and there’s 30 somewhere after it (?=.\*30)

Right after this you briefly talk about lookbehind and say it is the same thing but looks behind, without mentioning that it actually cannot do the same thing with non fixed lenght regular expressions (including quantifiers like *).

Comienza con el artículo “Lookahead and lookbehind” enlazado en el issue, especialmente con sus secciones sobre lookahead y lookbehind. Compara los ejemplos documentados con las restricciones de JavaScript sobre los patrones de longitud no fija en las expresiones lookbehind. Se considerará terminado cuando el artículo explique claramente la limitación y distinga el comportamiento de lookahead del comportamiento de lookbehind.