TypeScript 返回相同的嵌套对象 struct ，但类型不同

我正在使用这个函数，它重建初始对象，但递归地将每个值转换为BigNumbers.

export const castObjectValuesToBigNumber = function(initialObj: StringMap, nestedProp?: string) {

    let _castedObj: StringMap = {};

    for(const [property, value] of Object.entries(initialObj)) {

        if(typeof(value) === "object" && !(value instanceof BN)) {
            const newVal = castObjectValuesToBigNumber(value, property);
            _castedObj = { ..._castedObj, ...newVal };
        } else {
            if(nestedProp) {
                if(!_castedObj[nestedProp]) _castedObj[nestedProp] = {};
                _castedObj[nestedProp][property] = BigNumber.from(value.toString());
            } else {
                _castedObj[property] = BigNumber.from(value.toString());
            }
        }
    }

    return _castedObj;
}

我想让它的返回类型与initialObj类型相同，但将End值设置为BigNumber类型.

示例:

const myValue = {
   propertyA: new BN(105),
   propertyB: {
      propertyC: new BN(1),
      propertyD: new BN(2),
      propertyE: new BN(3)
   },
   propertyF: {
      propertyG: new BN(4)
   }
}

我希望如果我把这个值作为我的函数的一个参数，TypeScrip会自动返回这个类型:

{
   propertyA: BigNumber,
   propertyB: {
      propertyC: BigNumber,
      propertyD: BigNumber,
      propertyE: BigNumber
   },
   propertyF: {
      propertyG: BigNumber
   }
}

我try 了很多使用泛型类型和嵌套类型的方法，但我总是会遇到某种类型的错误.

Here is a Minimum Reproducible 示例:

/////////////////////
/// DECLARATIONS

interface StringMap { [key: string]: any }

class BN {
    value;
    constructor(num: number | string) {
        this.value = num;
    }

    _isBN() {
        return true;
    }
}

class BigNumber {
    value;
    constructor(num: number | string) {
        this.value = num;
    }

    _isBigNumber() {
        return true;
    }
}

const myValue = {
   propertyA: new BN(105),
   propertyB: {
      propertyC: new BN(1),
      propertyD: new BN(2),
      propertyE: new BN(3)
   },
   propertyF: {
      propertyG: new BN(4)
   }
};

/////////////////////
/// FUNCTION
export const castObjectValuesToBigNumber = function(initialObj: StringMap, nestedProp?: string) {

    let _castedObj: StringMap = {};

    for(const [property, value] of Object.entries(initialObj)) {

        if(typeof(value) === "object" && !(value instanceof BN)) {
            const newVal = castObjectValuesToBigNumber(value, property);
            _castedObj = { ..._castedObj, ...newVal };
        } else {
            if(nestedProp) {
                if(!_castedObj[nestedProp]) _castedObj[nestedProp] = {};
                _castedObj[nestedProp][property] = new BigNumber(value.toString());
            } else {
                _castedObj[property] = new BigNumber(value.toString());
            }
        }
    }

    return _castedObj;
}

/////////////////////
/// TEST

/*
    Result is of type StringMap while I would like it to be :

    {
        propertyA: BigNumber,
        propertyB: {
            propertyC: BigNumber,
            propertyD: BigNumber,
            propertyE: BigNumber
        },
        propertyF: {
            propertyG: BigNumber
        }
    }
    
*/

const myCastedValue = castObjectValuesToBigNumber(myValue);