本扩展实现了 » JavaScript对象符号（JSON） 数据转换格式. 解码分析器基于 Douglas Crockford 的 JSON_checker。
Note:
PHP implements a superset of JSON as specified in the original » RFC 4627 - it will also encode and decode scalar types and
NULL. RFC 4627 only supports these values when they are nested inside an array or an object.Although this superset is consistent with the expanded definition of "JSON text" in the newer » RFC 7159 (which aims to supersede RFC 4627) and » ECMA-404, this may cause interoperability issues with older JSON parsers that adhere strictly to RFC 4627 when encoding a single scalar value.