Lodash 4: How to compare two object keys and return differences?

Question

I have two objects like so:

originalObj:

{
    name: "Jane",
    fullName: "Jane Doe"
    nickname: "Janey"
    ...etc...
}

updatedObj:

{
    name: "Jane",
    fullName: "Jane Dawn", //<--this value changed
    nickname: "Janey"
    ...etc..
}

With lodash 4, how can I compare both objects and just return the updated values with key?

So, for example, I would expect to see:

{
    fullName: "Jane Dawn",
        ...etc...
}

My use case is that I want to show a "before" and "after" view to a user of existing database data and user-updated form data before submitting to a server.

https://stackoverflow.com/a/39813128/4758494 – Hassan Imam Sep 14 '21 at 15:14 — Hassan Imam, Sep 14 '21 at 15:14
that returned an object without the updated keys/values – redshift Sep 14 '21 at 15:29 — redshift, Sep 14 '21 at 15:29

score 3 · Accepted Answer · answered Sep 14 '21 at 17:20

If it's flat object, ie no nested objects or arrays, you can use _.pickBy() on the updated object, and take every property that is not equal to the similar property from the original object:

const originalObj = {"name":"Jane","fullName":"Jane Doe","nickname":"Janey"}
const updatedObj = {"name":"Jane","fullName":"Jane Dawn","nickname":"Janey"}

const result = _.pickBy(updatedObj, (v, k) => !_.isEqual(originalObj[k], v))

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js" integrity="sha512-WFN04846sdKMIP5LKNphMaWzU7YpMyCU245etK3g/2ARYbPK9Ub18eG+ljU96qKRCWh+quCY7yefSmlkQw1ANQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

If you need to compare nested objects, use a package, such as deep-object-diff .

Lodash 4: How to compare two object keys and return differences?

1 Answers1