//^([a-z0-9]{5,})$
//Use regex.test() for boolean result:
/^([a-z0-9]{5,})$/.test('hello1'); // false
/^([a-z0-9]{5,})$/.test('hello12'); // true
/^([a-z0-9]{5,})$/.test('hello123'); // true
//you could remove the () from regex since there's no need to capture it.