[nmcfarl]

> There's no need for comments unless you are trying to use it for something other than raw data.

Is this a true statement? Even books have margins, and word docs comments. I think it’s not infrequent that pure data calls for metadata to put it into context for future users of that data.

And in computing most "pure data" formats have had either comments - or schemas and specifications which outline which the contents. The later sure look like comments stored externally to the documents, from my perspective.

In general I do not think data is self describing, and thus must be commented on in some form to describe it.

[nonchalance]

You can represent annotations (which describe most of your examples) by adding keys:

    {
        "data": "some data",
        "data_comments": "here are my comments"
    }

[sixbrx]

Not transparent to actual clients of the data.

edit for clarity: You're assuming that the application code isn't doing something with each key that it reflectively sees in the object, e.g. creating database fields to match them, or launching missiles towards those destinations, etc.. If you wouldn't automatically add dummy elements to a hashmap or dictionary in Java or Python, then you shouldn't add keys in a javascript object, unless you control the source to the program that will processing the data. Even then you shouldn't, because it will become a habit to add comments this way, and that will bite you when an extra key does matter.

[dnautics]

or just use the key "comment" more than once, which is sort of a hybrid of the ideas.

[IanCal]

Parsers might throw an error on duplicate keys, or launch emacs solving the towers of hanoi.