How to determine whether a string is valid JSON?

Question

Does anyone know of a robust (and bullet proof) is_JSON function snippet for PHP? I (obviously) have a situation where I need to know if a string is JSON or not.

Hmm

Answer 1

What about using json_decode, which should return null if the given string was not valid JSON-encoded data ?

See example 3 on the manual page :

// the following strings are valid JavaScript but not valid JSON

// the name and value must be enclosed in double quotes
// single quotes are not valid 
$bad_json = "{ 'bar': 'baz' }";
json_decode($bad_json); // null

// the name must be enclosed in double quotes
$bad_json = '{ bar: "baz" }';
json_decode($bad_json); // null

// trailing commas are not allowed
$bad_json = '{ bar: "baz", }';
json_decode($bad_json); // null