Get the property of the difference between two objects in javascript

Question

Let's say that I have an object which looks like this:

{
  prop1: false,
  prop2: false,
  prop3: false
}

and another object which looks like this:

{
  prop1: false,
  prop2: true,
  prop3: false
}

where the difference is within the prop2 property. Is there any way or library (vanilla preferred though) which will compare the two objects, find the property with the different value, and return the property name (in this case prop2)?

I have tried using the difference and differenceBy functions in lodash to no success. Any help or suggestions will be greatly appreciated!

score 41 · Accepted Answer · answered Oct 25 '17 at 11:02

41

You could filter the keys (assuming same keys) by checking the unequal value.

var obj1 = { prop1: false, prop2: false, prop3: false },
    obj2 = { prop1: false, prop2: true, prop3: false },
    difference = Object.keys(obj1).filter(k => obj1[k] !== obj2[k]);
    
console.log(difference);

answered Oct 25 '17 at 11:02

Nina Scholz

376,160
25
347
392

1

This solution does not take in account that the input could be a nested object. A better solution could be the one here https://stackoverflow.com/questions/30476150/javascript-deep-comparison-recursively-objects-and-properties, adding the keys differences as result. – loretoparisi Apr 09 '19 at 10:31
4

@loretoparisi, this solution takes exactly the object of the op, not a not given nested object. – Nina Scholz Apr 09 '19 at 10:40
you are right, I mean to be as generic as possible. – loretoparisi Apr 09 '19 at 10:43
@NinaScholz so I have asked new question here https://stackoverflow.com/questions/55591096/compare-nested-objects-in-javascript-and-return-keys-equality – loretoparisi Apr 09 '19 at 10:52
[Not work for KeyboardEvent object](https://stackoverflow.com/questions/59235864/object-keyskeyboardevent-only-get-one-istrusted-key-rather-than-all-keys) – illiterate Dec 08 '19 at 13:30

Zoren Konte · Answer 2 · 2021-06-19T05:29:35.380

This function will extract all the difference between two objects. It will also works on nested objects. This code uses some lodash functions. (function names that starts with "_.")

function difference(object, base) {
    function changes(object, base) {
        return _.transform(object, function(result, value, key) {
            if (!_.isEqual(value, base[key])) {
                result[key] = (_.isObject(value) && _.isObject(base[key])) ? changes(value, base[key]) : value;
            }
        });
    }
    return changes(object, base);
}

score -9 · Answer 3 · answered Oct 25 '17 at 10:50

-9

this is the fastest and simplest method

var a ={
  prop1: false,
  prop2: false,
  prop3: false
}

var b={
  prop1: false,
  prop2: true,
  prop3: false
}

 JSON.stringify(a) === JSON.stringify(b)

this return false. order of props is also important

answered Oct 25 '17 at 10:50

Rahul

462
1
4
16

1

This does not answer the question – tim-phillips Aug 29 '18 at 22:08

Get the property of the difference between two objects in javascript

3 Answers3

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