Requirement: Compare the difference between two objects and return the difference object.
This function I made will find new or changed values, and new elements of the array.

function isObject(object) {
    return object !== null && typeof object === 'object' && !Array.isArray(object);
}

function compareObject(data, lastData, diff = {}) {
    const keys = Object.keys(data);
    for (let key of keys) {
        if (lastData === undefined) {
            lastData = {};
        }
        if (lastData[key] === undefined) {
            diff[key] = JSON.parse(JSON.stringify(data[key]));
            continue
        };
        if (Array.isArray(data[key])) {
            if (data[key].length !== lastData[key].length) {
                const diffArr = data[key].filter((item, index) => lastData[key][index] === undefined)
                diff[key] = diffArr;
                continue
            }
        };
        if (!isObject(data[key]) && JSON.stringify(data[key]) !== JSON.stringify(lastData[key])) {
            diff[key] = data[key];
            continue
        }
        if (isObject(data[key])) {
            if (Object.keys(compareObject(data[key], lastData[key])).length !== 0) {
                diff[key] = compareObject(data[key], lastData[key]);
                continue
            }
        };
    }
    return diff
}

origin example as below:

const oldData = {
    account_info: {
        age: 30,
        favor: ["coding", "music"],
        cars: [{ brand: 'toyota', count: 1 }],
        room: {
            A01: "test1",
        }
    },
    server: {
        os: "Linux",
        cloud: "gcp"
    }
}

const newData = {
    account_info: {
        age: 30,
        favor: ["coding", "music", "see movie"],
        cars: [{ brand: 'toyota', count: 2 }, { brand: 'KIA', count: 1 }],
        room: {
            A01: "test2",
            A02: "black",
            A03: "white"
        }
    },
    "server": {
        "os": "Linux",
    }
}

// result(without first object value changed in array)
// {
//     account_info: {
//       favor: [ 'see movie' ],
//       cars: [ { brand: 'KIA', count: 1 } ],
//       room: { A01: 'test2', A02: 'black', A03: 'white' }
//     }
// }

But new demand is also find out which object in the array has changed only value??
How can I extend this function?
Thanks!!