typescript - 如何使用 Object.keys() 键入嵌套对象？

Question

我正在使用嵌套对象并尝试使用 Object.keys() 和 forEach() 获取属性。问题是当我想访问嵌套键filteringState[item][el]时。

如何输入这样的函数？

interface InitialStateTypes {
    country: {
        "italy": boolean,
    },
    board: {
        "full": boolean,
    },
    transport: {
        "bus": boolean,
        "own": boolean
    },
}

interface FilteringDataTypes {
    country: string[],
    board: string[],
    transport: string[],
}

const collectFilteringData = (filteringState: InitialStateTypes) => {
    let filteringData = <FilteringDataTypes>{};

    Object.keys(filteringState).forEach((item) => {
        Object.keys(filteringState[item]).forEach((el) => {
            if (filteringState[item][el]) {
                if (!filteringData[item]) {
                    filteringData[item] = [el];
                } else {
                    filteringData[item] = [...filteringData[item], el];
                }
            }
        });
    });
    return filteringData;
};


export default collectFilteringData;

Answer 1

您可以使用keyof运算符。

示例:

type Point = { x: number; y: number };
type P = keyof Point;

这里有更多详细信息:https://www.typescriptlang.org/docs/handbook/2/keyof-types.html

嵌套数据:

type Point = { test: {x: number; y: number} };
type P = keyof Point["test"];