function-type-expressions

When using function expressions (not statements), you can apply a type to the entire function. This reduces repetition, improves type safety, and makes code more readable.

Without the function type, this would only error at call sites.

Response: With shared signatures, centralizing the type removes noise.

在編寫具有相同簽名的多個函數時使用。在實現回調時使用。在匹配現有函數類型時使用。 來源：marius-townhouse/effective-typescript-skills。