How to get the difference between two objects?

If I have two objects:

const objA = { name: 'Tom', age: '20', location: 'London' };
const objB = { name: 'Jimmy', age: '35', occupation: 'Welder', hobbies: ['Football'] }

How can I get only the values that are only present in objA and not in objB, I want the result to be:

{
    location: 'London'
}

Is there a method in Lodash for that?

Solution

You can use _.pickBy() and _.has() to get the desired result using lodash.

We'll use the predicate: (value, key) => !_.has(objB, key) to return entries only present in objA.

const objA = { name: 'Tom', age: '20', location: 'London' };
const objB = { name: 'Jimmy', age: '35', occupation: 'Welder', hobbies: ['Football'] }

const difference = _.pickBy(objA, (value, key) => !_.has(objB, key));
console.log('Difference:', difference)

<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>

You can also do this in vanilla JavaScript using Object.entries(), Object.fromEntries() and Array.filter():

const objA = { name: 'Tom', age: '20', location: 'London' };
const objB = { name: 'Jimmy', age: '35', occupation: 'Welder', hobbies: ['Football'] }

const difference = Object.fromEntries(
    Object.entries(objA).filter(([key, value]) => {
        return !objB.hasOwnProperty(key);
    })
);

console.log('Difference:', difference)