Because of these two invisible Unicode characters, JSON is not a subset of JavaScript. Close, but no cigar.
In most applications, you won’t notice this issue. First of all, the line separator and the paragraph separator isn’t exactly widely used. Secondly, any proper JSON parser will have no problems with parsing it.
However, when you’re dealing with JSONP there’s no way around: You’re forced to use the JavaScript parser in the browser. And if you’re sending data that other have entered, a tiny U+2028 or U+2029 might sneak in and break your pretty cross-domain API.
via Timeless – JSON: The JavaScript subset that isn’t. Wikipedia is wrong man.