How to determine whether it is in json format in PHP7?

A function I found online:

<code>function is_json($string) 
{
 json_decode($string);
 return (json_last_error() == JSON_ERROR_NONE);
}

$str = '{id:23,name:"test"}';
$str = "{'id':23,'name':'test'}";
为什么在PHP7，均不是合法的json格式呢？？
有没有靠谱的方法？？</code>

Reply content:

A function I found online:

<code>function is_json($string) 
{
 json_decode($string);
 return (json_last_error() == JSON_ERROR_NONE);
}

$str = '{id:23,name:"test"}';
$str = "{'id':23,'name':'test'}";
为什么在PHP7，均不是合法的json格式呢？？
有没有靠谱的方法？？</code>

In JSON format, both key and value must be in double quotes...

return json_encode($json)!==false

PHP7 adopts stricter JSON rules, single quotes can no longer be used for references and field names.

<code>var arr = {id:23,name:'test'}; //键名不用引号,值用单引号,在JS中,这样写都合法
alert(JSON.stringify(arr)); //但合法的JSON字符串应该是stringify后的模样 {"id":23,"name":"test"}</code>