# isJSON > Test if a value is a parseable JSON string.
## Usage ```javascript var isJSON = require( '@stdlib/assert/is-json' ); ``` #### isJSON( value ) Tests if a `value` is a parseable JSON `string`. ```javascript var value = '{"a":5}'; var bool = isJSON( value ); // returns true ```
## Notes - The implementation validates that the input `value` is a `string` literal. For all other inputs, the method returns `false`. - The implementation validates that a `string` begins with either `[` or `{` and ends with a corresponding `]` or `}`, respectively. Hence, the method will return `false` for the following `strings`, despite `JSON.parse` accepting their input: - `''` (e.g., `'5'`) - `''` (e.g., `'true'`) - `'null'` - The implementation wraps `JSON.parse` inside a `try/catch`. Hence, this function cannot be optimized by the compiler during runtime. Nevertheless, using this function is better than embedding a `try/catch` within a larger `function` which could be optimized in the absence of a `try/catch`.
## Examples ```javascript var isJSON = require( '@stdlib/assert/is-json' ); var bool = isJSON( '{"a":5}' ); // returns true bool = isJSON( '{a":5}' ); // returns false ```