Generic deep diff between two objects

deepDiff.js

/*
    Credits to sbgoran (https://jsfiddle.net/user/sbgoran/fiddles/)
    https://jsfiddle.net/sbgoran/kySNu/
*/

var deepDiffMapper = function() {
    return {
        VALUE_CREATED: 'created',
        VALUE_UPDATED: 'updated',
        VALUE_DELETED: 'deleted',
        VALUE_UNCHANGED: 'unchanged',
        map: function(obj1, obj2) {
            if (this.isFunction(obj1) || this.isFunction(obj2)) {
                throw 'Invalid argument. Function given, object expected.';
            }
            if (this.isValue(obj1) || this.isValue(obj2)) {
                return {
                    type: this.compareValues(obj1, obj2),
                    data: (obj1 === undefined) ? obj2 : obj1
                };
            }

            var diff = {};
            for (var key1 in obj1) {
                if (this.isFunction(obj1[key1])) {
                    continue;
                }

                var value2 = undefined;
                if ('undefined' != typeof(obj2[key1])) {
                    value2 = obj2[key1];
                }

                diff[key1] = this.map(obj1[key1], value2);
            }
            for (var key2 in obj2) {
                if (this.isFunction(obj2[key2]) || ('undefined' != typeof(diff[key2]))) {
                    continue;
                }

                diff[key2] = this.map(undefined, obj2[key2]);
            }

            return diff;

        },
        compareValues: function(value1, value2) {
            if (value1 === value2) {
                return this.VALUE_UNCHANGED;
            }
            if (this.isDate(value1) && this.isDate(value2) && value1.getTime() === value2.getTime()) {
                return this.VALUE_UNCHANGED;
            }
            if ('undefined' == typeof(value1)) {
                return this.VALUE_CREATED;
            }
            if ('undefined' == typeof(value2)) {
                return this.VALUE_DELETED;
            }

            return this.VALUE_UPDATED;
        },
        isFunction: function(obj) {
            return {}.toString.apply(obj) === '[object Function]';
        },
        isArray: function(obj) {
            return {}.toString.apply(obj) === '[object Array]';
        },
        isObject: function(obj) {
            return {}.toString.apply(obj) === '[object Object]';
        },
        isDate: function(obj) {
            return {}.toString.apply(obj) === '[object Date]';
        },
        isValue: function(obj) {
            return !this.isObject(obj) && !this.isArray(obj);
        }
    };
}();

var result = deepDiffMapper.map(
    {
        a:'i am unchanged',
        b:'i am deleted',
        e:{ a: 1,b:false, c: null},
        f: [1,{a: 'same',b:[{a:'same'},{d: 'delete'}]}],
        g: new Date('2017.11.25')
    },
    {
        a:'i am unchanged',
        c:'i am created',
        e:{ a: '1', b: '', d:'created'},
        f: [{a: 'same',b:[{a:'same'},{c: 'create'}]},1],
        g: new Date('2017.11.25')
    }
);
console.log(result);