How to make comment in JSON file

comments-trick.json

{
    "//field": "These 'double quote' 'double quote' are used as comments, because JSON doesnt' allow comment",
    "field": {},
    "#another-field": "Another comment",
    "another-field": {},
    "/*stuff": "Be careful to use them when you have full control of the content :)",
    "stuff": [],
    "bla": "bla"
}

Aww damn! I landed on this page from a google search looking for an easy workaround

Another way, if you have a context checker that doesn't allow empty quote strings for declarations:

{
    "_comment":  "Comments with // or /**/ are NEVER used in a JSON file!!!",
    "regulardata": "stuff"
}

Hope that helps. Just have your processing code lack processing for it, and it works fine.

JSON (& strictly-linted JS) don't allow duplicate keys of objects, so add a unique letter or number to make it validate. This is a trick I've seen somewhere in popular code but can't remember where, sorry. I think the convention of using a "//" as the basis for comment names seems fairly sensible & terse, and should make it easy to programmatically update current JSON configs to some better format in future.

{
    "//a": "This is the first comment."
    "//b": "...and this is the second." 
}

The JSON should all be data, and if you include a comment, then it will be data too.

You could have a designated data element called "_comment" (or something) that would be ignored by apps that use the JSON data.

You would probably be better having the comment in the processes that generates/receives the JSON, as they are supposed to know what the JSON data will be in advance, or at least the structure of it.

{
"_comment": "comment text goes here...",
"Key":"value"
}

@twome's comment here is the best suggestion. I'd give it a 👍 if I could!

nothing works in php (json_decode) - all comments are still in data

Yeah because it's a trick, not real comment. JSON specs just don't have comments...

None of these is how I would have done it,
I would have gone for something like this instead:

{
    "Comments": [
        "Lorem ipsum dolor sit amet,",
        "consectetur adipiscing elit.",
        "Suspendisse vitae risus ligula.",
        "Fusce vel urna turpis."
    ]
}

Then you won't have to think about making identifiers for every line, and it validates.

JSON 5 (https://json5.org/) does support comments. However, support for it is limited. E.g. PHP does not support it yet.

You can use:

/*
{
"Comments": [
"Lorem ipsum dolor sit amet,",
"consectetur adipiscing elit.",
"Suspendisse vitae risus ligula.",
"Fusce vel urna turpis."
]
}
*/

other options
put all the comment in the key :-)
there should be less duplicates problems
ex

{ 
  "// this is fun":"",
  "// this is also fun": "",
  "whatever": {
    "// other scope": "",
    "// this is fun": ""
  },
  "port": 8090, "// can't use native port":""
}