Function isJsonString

isJsonString(text?: null | string): boolean
Returns whether the given string is a JSON string
Parameters
- Optionaltext: null | string
  the string to check
Returns boolean
whether the given object is a JSON string
Author
David Hsing
Example
```
isJsonString(`{"foo": "bar"}`);    // true
isJsonString(`[{"foo": "bar"}]`);    // true
isJsonString(`[{"foo": "bar"}, {"hello": "world"}]`);    // true
```