Transform values inside object of object

November 2, 2022

I would like to transform values inside an object of an object. Something like this:

Initial object:

const studentDetails = {
   'details1': {Name: "John", CountryName: "US", value: 1},
   'details2': {Name: "David", CountryName: "AUS", value: 2},
   'details3': {Name: "Bob", CountryName: "UK", value: 3},
};

Transformed object:

{
   'details1': {Name: "John", CountryName: "US", value: 2},
   'details2': {Name: "David", CountryName: "AUS", value: 3},
   'details3': {Name: "Bob", CountryName: "UK", value: 4},
};

I did something like this already but could not figure it out

Object.fromEntries(Object.entries(studentDetails).map(([key,
value]) => [key, some data transformation on value]))

>Solution :

You can do something like this. We define a transformValue function which takes in the student details object and any transform function. Then applies the transform function on every value and returns the whole transformed details object.

const studentDetails = {details1: { Name: "John", CountryName: "US", value: 1 }, details2: { Name: "David", CountryName: "AUS", value: 2 }, details3: { Name: "Bob", CountryName: "UK", value: 3 }};

const transformValue = (details, transform) => {
    return Object.entries(details).reduce((acc, [key, detail]) => {
        acc[key] = {
            ...detail,
            value: transform(detail.value)
        }

        return acc;
    }, {});
};

console.log(transformValue(studentDetails, (val) => val + 1)); // Increments value
console.log(transformValue(studentDetails, (val) => val * val)); // Squaring values