JSON5 parse constructs a Javascript object, which can in turn be serialized by JSON 4 into valid plain JSON string. That's not an invalid way of converting the two objects.

JSON.stringify is part of the standard JS spec: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

JSON5.parse() is part of JSON5's API: https://json5.org/#json5parse

So any project that includes both standard JS and JSON5 could literally copy and paste this code. You're still importing JSON5, but you would presumably have to do that anyways to use JSON5.

> So any project that includes both standard JS and JSON5 could literally copy and paste this code

is not a convincing reply to

> so parsers already exist in every language

Personally, I like some of the ideas of JSON5, but it isn't compatible with JSON as implemented. Altering existing systems to use it isn't as trivial as you imply. And requires taking on new dependencies.

You'd have to rewrite anything using json_encode() and json_decode() in PHP, or the equivalent standard functions/methods in Python, C#, etc. And also take on another dependency. And maybe lose performance.

And then you sometimes may have to know whether you're dealing with JSON or JSON5, and what the program on the other end of the line produces or expects and can handle.

For new greenfield projects it might be worthwhile. But most of the world runs on legacy code and many prefer to stick to the standards and minimize dependencies. So it's not that simple.

That doesn't mean it's bad though. Like anything else in software, it's a trade-off.

What about the vast majority of languages that aren’t JavaScript?