Typescript - 來自嵌套箭頭的 ReturnType function

Question

我有一個描述 object 和嵌套 function 的類型：

type EntitiesGetters = {
  getCategories: (state: EntitiesState) => (panelID: EntityID) => CategoryGroup;
};

這是將此類型應用於 object 的示例：

export const entitiesGetters: EntitiesGetters = {
  getCategories: (state) => (panelID) => {
    const data = {} as GET_TYPE;

    for (const key in state.categories) {
      const category = state.categories[key];
      if (category.entities.panel === panelID) {
        data[Object.keys(data).length] = category;
      }
    }

    return data;
  },
};

如何在 GET_TYPE 中獲取我需要的類型（對應於類型“CategoryGroup”）？

如果我使用了錯誤的方法，請糾正我。

Answer 1

您應該能夠使用 TypeScript 內置ReturnType ：

export const entitiesGetters: EntitiesGetters = {
  getCategories: (state) => (panelID) => {
    const data: ReturnType<ReturnType<EntitiesGetters["getCategories"]>> = {}

    // ...

    return data;
  },
};