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by CanSpice 4698 days ago
Given the RFC says "The names within an object SHOULD be unique", there's nothing stopping me from writing a parser that takes the first name/value pair and throwing all the others on the floor. Or even better, picks a random name/value pair when the same name appears. Both of these behaviours are allowed by the RFC, and would break this hack.

Putting comments into JSON in this way is a hack and shouldn't be used by anybody who has any interest in writing maintainable software. Relying on ambiguities in an RFC and someone saying "JSON parsers work the same way" is a good way to end up with a really obscure bug in the future.
2 comments
serichsen 4698 days ago
At least in ECMA-262 5, Ch. 15.12.2, there is a NOTE: "In the case where there are duplicate name Strings within an object, lexically preceding values for the same key shall be overwritten."

It still does not feel right.

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bzbarsky 4698 days ago
Assuming you mean RFC 4627, you're quoting the restrictions on what character streams can be called "JSON". The "should" means that if your names are not unique you can still call it "JSON", but you should think twice about it.

The parsing behavior for JSON is not defined at all in RFC 4627, actually. Browsers (and Node, since it's using a browser js engine) use the parsing specification in ECMA-262 edition 5 section 15.12.2.

Note that ES5 section 15.12 in general is much stricter than RFC 4627, as it explicitly points out if you read it.

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