```ts
export function caseCount(text: string): number[] {
  let capital = 0;
  let lowercase = 0;

  for (const char of text) {
    if (char >= 'A' && char <= 'Z') {
      capital++;
    } else if (char >= 'a' && char <= 'z') {
      lowercase++;
    }
  }

  return [capital, lowercase];
}
```