current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to Mongo Client.connect. code example
Example: DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
mongoose.connect("mongodb://localhost:27017/YourDB", { useNewUrlParser: true });