Function isJSON

isJSON<T = unknown>(str: string): IsJSONResult<T>
Checks if a string contains valid JSON and optionally parses it.

Uses a regex pre-check to quickly eliminate non-JSON strings before attempting to parse. Returns both a boolean flag and the parsed result if successful.
Type Parameters
- T = unknown
  The expected type of the parsed JSON (default: unknown)
Parameters
- str: string
  The string to check and parse
Returns IsJSONResult<T>
Object with isJSON boolean and optional parsed value
Example
```
const result = isJSON<{ name: string }>('{"name": "Alice"}');
if (result.isJSON) {
  console.log(result.parsed.name); // "Alice"
}

const invalid = isJSON('not json');
console.log(invalid.isJSON); // false
```
- Defined in is-json.ts:31