coolFunction

const testFunction = () => {

    let propertiesA = {a: 1, b: 'A', c: 5, config: {a: 2}};

    let propertiesB = {a: 2, d: 4, f: 6, person: 'Tom', config: {a:5, b: 10}};

    let newObject = coolfunction(propertiesA, propertiesB)

    return coolfunction(objA, objB);
};

function coolfunction(objA, objB) {
    let  s, next, empty = {};

    for (let name in objB) {
        s = objB[name];

        if (!(name in objA) || (objA[name] !== s && (!(name in empty) || empty[name] !== s))) {

            if (typeof s === 'object' && !(s instanceof Array) && s !== null) {

                if (!(name in objA) || !objA[name]) {
                    objA[name] = {};
                }

                coolfunction(objA[name], s);

            } else {

                objA[name] = s;

            }
        }
    }

    return objA
}