alt Hacker NewsIt is more that people made comments semantically important, e.g. a tool which did not interpret comments would not correctly interpret the data in the document.
This actually would put JSON in a worse place than XML - while XML has an overly complex infoset, that infoset is actually defined and standardized. Representing "a property with a comment on the property name and one before and after the property value" so that information is not lost in parsing would explode the complexity needed for an "interoperable" JSON library.
if someone wants to create some sort of scheme where they do "createdAt$date" as a property name to indicate the value is to be interpreted in some agreed-upon date format, that at least doesn't lose data if the JSON data doesn't understand that scheme, or require a new custom parser in order to properly interpret that data, compared to something like /* $type: date */ "createdAt" :...
why would you need that complex representation in the interoperable library instead of a much simpler one: a property, a comment, a comment, a value, a comment, ...?
This doesn't explode anything and you don't need to lose any data, so the monstrosity of XML still has no benefit, and neither does "createdAt$date", which would need a custom library anyway, so it doesn't matter where you insert your types