I think the article's point was that Unicode characters U+2028 and U+2029 are illegal in JavaScript string literals.
Yet, the JSON specification (RFC 4627) officially allows them to exist in JSON string literals:
"All Unicode characters may be placed within the quotation marks except for the characters that must be escaped: quotation mark, reverse solidus, and the control characters (U+0000 through U+001F)."
So with U+2028 or U+2029 you can construct a valid JSON object that JavaScript can't parse.
Comments
Yawn. JSON isn't valid Javascript, but it sure is a valid Javascript data structure.
I often use code like
and be 100% sure I'm generating perfectly valid Javascript, no matter what is in $data. (Well, apart from circular references, and "resources".)I think the article's point was that Unicode characters U+2028 and U+2029 are illegal in JavaScript string literals.
Yet, the JSON specification (RFC 4627) officially allows them to exist in JSON string literals:
"All Unicode characters may be placed within the quotation marks except for the characters that must be escaped: quotation mark, reverse solidus, and the control characters (U+0000 through U+001F)."
So with U+2028 or U+2029 you can construct a valid JSON object that JavaScript can't parse.