NodeJS Mongoose & Mongo Db Connection Issue - node.js

Question

I am new to mongodb and I have setup on mac os and it's successfully done. Now when I run my node js application with mongoose to connect with mongodb, It's always show a connecting state.
I am using below code to connect the database.
module.exports = function() {
/**
* Requiring this module will populate the mongoose connection pool.
* Any models defined on mongoose will be ready to use (mongoose is
* a singleton).
*/
var mongoose = require('mongoose');
var logger = include('logger.js');
// attempt to connect to the database server
logger.info("DB CONNECTION ", {DB: global.settings.DB, options: global.settings.DbOptions});
//console.log("DB CONNECTION ", {DB: global.settings.DB, options: global.settings.DbOptions});
mongoose.connect('mongodb://localhost/circleweb');
mongoose.connection.on("open", function(ref) {
console.log("Connected to mongo server.");
});
mongoose.connection.on('connected', function () {
console.log('connected');
console.log('Mongoose default connection open to ' + global.settings.DB);
});
mongoose.connection.on('error', function (error) {
logger.error(error);
console.log('Mongoose default connection error: ' + error.err);
// if the database cannot be connected to. We are going to throw
// an error. This will be caught by the error handler
throw error.err;
});
mongoose.connection.on('disconnected', function () {
console.log('Mongoose default connection disconnected');
});
process.on('SIGINT', function () {
mongoose.connection.close(function () {
console.log('Mongoose default connection disconnected through app termination');
process.exit(0);
});
});
console.log(mongoose.connection.readyState);
return mongoose.connection;
}();
And When i run my application I am not getting any callback from mongoose not even any error.
Also when I run mongod on terminal it shows correct output and also it's accepting the connection from nodejs application but not connecting with it.
Any help would be appreciate

Answer 1

Because console.log(mongoose.connection.readyState) is running synchronously - it will get executed first - before the mongoose.connection.on async calls, which means that the state is 2 or connecting.
Surround it with a timeout and you will get the expected 1 value:
setTimeout( () => {
console.log(mongoose.connection.readyState); // prints 1
}, 2000);
Or print the state within the async call:
mongoose.connection.on('connected', function () {
console.log(`STATE: `, mongoose.connection.readyState);
console.log('connected');
console.log('Mongoose default connection open to ' );
});