How to modify each value of a nested object?

Issue

How can I multiply every nested value of this object by X (e.g. 0.5)?

const myObject = {
    base: {
        serving: {
            size: 100
        }
    },
    fat: {
        acids: {
            monoUnsaturatedFattyAcids: 12
            polyUnsaturatedFattyAcids: 3
            saturatedFattyAcids: 2
        },
    }
}

The object is sometimes nested up to 10 levels deep.

Solution

You could define a generator that will provide an iterator over every nested key/value pair (together with the nested object), so that you can do what you want with it inside a for loop:

function * iter(obj) {
    for (let [key, value] of Object.entries(obj)) {
        if (Object(value) !== value) yield [obj, key, value];
        else yield * iter(value);
    }
}

// demo
const myObject = {
    base: {
        serving: {
            size: 100
        }
    },
    fat: {
        acids: {
            monoUnsaturatedFattyAcids: 12,
            polyUnsaturatedFattyAcids: 3,
            saturatedFattyAcids: 2
        },
    }
};

for (let [obj, key, value] of iter(myObject)) {
    if (typeof value === "number") obj[key] *= 0.5; // multiply by 0.5
}
// The object has been mutated accordingly
console.log(myObject);

Answered By - trincot