JSFiddle - React, Tailwind, and code Playground

JavaScript

var obj1 = {
    astring: "stringobj1",
    anum: 1,
    anum2: 2,
    data1: {
        data11: [
            {
            id: 2,
            comment: "comment2"},
        {
            id: 3,
            comment: "comment3"},
        {
            id: 4,
            comment: "comment4"}],
        data12: ""
    },
    data: [
        {
        id: 1,
        comment: "comment1"},
    {
        id: 2,
        comment: "comment2"},
    {
        id: 3,
        comment: "comment3"}
    ]
};

var obj2 = {
    anum2: 3,
    astring: "stringobj2",
    data1: {
        data11: [
            {
            id: 2,
            comment: "comment12"},
        {
            id: 3,
            comment: "comment13"},
        {
            id: 4,
            comment: "comment14"}],
        data12: ""
    },
    data: [
        {
        id: 2,
        comment: "comment2"},
    {
        id: 3,
        comment: "comment3"},
    {
        id: 4,
        comment: "comment4"}
    ],
    data2: [
        {
        id: 2,
        comment: "comment2"},
    {
        id: 3,
        comment: "comment3"},
    {
        id: 4,
        comment: "comment4"}]
};

$(document).ready(function() {
    console.log(mergeDeep(obj1, obj2));
});

    function mergeDeep(o1, o2) {
        var tempNewObj = o1;

        //if o1 is an object - {}
        if (o1.length === undefined && typeof o1 !== "number") {
            $.each(o2, function(key, value) {
                if (o1[key] === undefined) {
                    tempNewObj[key] = value;
                } else {
                    tempNewObj[key] = mergeDeep(o1[key], o2[key]);
                }
            });
        }

        //else if o1 is an array - []
        else if (o1.length > 0 && typeof o1 !== "string") {
            $.each(o2, function(index) {
                if (JSON.stringify(o1).indexOf(JSON.stringify(o2[index])) === -1) {
                    tempNewObj.push(o2[index]);
                }
            });
        }

       ...