How to compare selected keys of different objects javascript

Question

I want to compare some selected fields of two objects.

E.g

const a = {type: "media", value: "TV"}
const b = {type: "media", value: "TV", name: "John"}

Can we have something to compare these two object with some specific keys like

const keys = [type, value]
compare(a, b, keys);

I just need to know some best practices to handle this logic and wants to avoid simple loops. Do we have any lodash lib for that ? Or any JavaScript ES6 function.

FYI: this is just simple example my real time scenario are far very complex.

Updates: This is what I have tried

Values are coming from react state and I am building my object E.g

const myObject = {a: aVal, b: bVal, c: cVal .......}
const compareObject = compareObject.exclude(the keys which I dont need) // example

const result = isEqual(myObject, compareObject)

Thanks

what result do you expect? a boolean value? what have you tried? — Nina Scholz
– Nina Scholz, Commented Jan 21, 2020 at 10:36
Yes boolean. Let me update my question about what I have tried. — Qubaish Bhatti
– Qubaish Bhatti, Commented Jan 21, 2020 at 10:38

Ori Drori · Accepted Answer · 2020-01-21 18:49:31Z

1

Use _.pick() to get the properties from the 2nd object (b), and then use _.isMatch() to make a partial deep comparison of the values (only the values of b that exist in a).

Note: _.isEqual() will work for nest structures as well - see the comparison between a & c.

const compare = (a, b, keys) => _.isMatch( // check deep equality
  a, // get properties from a
  _.pick(b, keys), // get properties from b
)

const a = { type: "media", value: "TV", name: { first: "John" } };
const b = { type: "media", value: "TV", name: "John" };
const c = { type: "media", value: "TV", name: { first: "John" } };

console.log(compare(a, b, ['type', 'value'])); //  true
console.log(compare(a, b, ['type', 'name']));  // false
console.log(compare(a, c, ['type', 'name']));  // true

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>

edited Jan 21, 2020 at 18:49

answered Jan 21, 2020 at 18:43

Ori Drori

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1 Comment

Qubaish Bhatti Over a year ago

Thanks. That is what I am looking for.

Nina Scholz · Accepted Answer · 2020-01-21 10:38:26Z

1

You could check every property of both objects.

const
    compare = (a, b, keys) => keys.every(k => a[k] === b[k]),
    a = { type: "media", value: "TV" },
    b = { type: "media", value: "TV", name: "John" };

console.log(compare(a, b, ['type', 'value'])); //  true
console.log(compare(a, b, ['type', 'name']));  // false

answered Jan 21, 2020 at 10:38

Nina Scholz

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