a way to combine/merge objects in json

I have this inconvenient output of data, like this:

[
    {
        "object_a": {
            "1": "some value of 1",
            "2": "some value of 2",
            "3": ""
        },
        "obejct_b": {
            "1": "",
            "2": "",
            "3": "some value of 3"
        },
        ..some other objects..
    }
    {
        "object_a": {
            "1": "some value of 1",
            "2": "",
            "3": "some value of 3"
    },
        "obejct_b": {
            "1": "",
            "2": "some value of 2",
            "3": ""
        },
        ..some other objects..
    }
    {
        "object_a": {
            "1": "",
            "2": "some value of 2",
            "3": ""
        },
        "obejct_b": {
            "3": "some value of 3",
            "1": "some value of 1",
            "2": ""
        },
        ..some other objects..
    }
]

I don't know what more to add. It looks straightforward as it is.
Unfortunately, I cannot change the output format.
The problem is that some data is in "object_a" and some in "object_b"

The desired output would be like:

[
    {
        "object": {
            "1": "some value of 1",
            "2": "some value of 2",
            "3": "some value of 3"
        }
        ..some other objects..
    }
	{
        "object": {
            "1": "some value of 1",
            "2": "some value of 2",
            "3": "some value of 3"
        },
        ..some other objects..
    }
        {
        "object": {
            "2": "some value of 2",
            "3": "some value of 3",
            "1": "some value of 1",
        },
        ..some other objects..
    }
]

I couldn't find a way to combine/merge two objects together, with jQuery.

Thanks.

Some assumptions must be made:

• Every object in the top-level array will have the same two (and only these two) properties object_a and obejct_b [sic].
• Every object_a and obejct_b will have the same set of properties.
• For any key in an object_a that is an empty string, the value in the "merged" result should be that of the corresponding obejct_b.

With these assumptions, I would use the following code.
(Note that I have left as is the typo in obejct_b.)

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

const output = [
{
"object_a": {
"1": "some value of 1",
"2": "some value of 2",
"3": ""
},
"obejct_b": {
"1": "",
"2": "",
"3": "some value of 3"
},
"some other object": {
"foo" : "bar"
}
},
{
"object_a": {
"1": "some value of 1",
"2": "",
"3": "some value of 3"
},
"obejct_b": {
"1": "",
"2": "some value of 2",
"3": ""
}
},
{
"object_a": {
"1": "",
"2": "some value of 2",
"3": ""
},
"obejct_b": {
"3": "some value of 3",
"1": "some value of 1",
"2": ""
}
}
];
const merged = output.map(item => {
// assumes object_a and obejct_b have the same keys
const mergedAB =  Object.keys(item.object_a).reduce((acc, key) => {
// assuming typo in "obejct_b" is intentional
acc[key] = item.object_a[key] || item.obejct_b[key];
return acc;
}, {});
const others = { ...item };
delete others.object_a;
delete others.obejct_b;
return {
object: mergedAB,
...others
}
});
document.body.innerHTML = `<pre>${JSON.stringify(merged, null, 2)}</pre>`;

<!-- end snippet -->