[JS] Recursive object assign

function assign (obj1, obj2) {
    if (!obj1) return obj2;
    if (!obj2) return obj1;

    let result = {};
    for (let key in obj1) {
        if (key in obj2) {
            if (typeof obj2[key] == 'object') result[key] = assign(obj1[key], obj2[key]);
            else result[key] = obj2[key];
        } else result[key] = obj1[key];
    }

    for (let key in obj2) {
        if (!result[key]) result[key] = obj2[key];
    }
    return result;
}

module.exports = assign;