test.js

var mongoose = require('mongoose');
var dbURL = 'mongodb://localhost:27017/testtest';

var retryMaxAttempt = 60;
var retryInterval = 1000;
var retryCountFirstConnect = 0;

mongoose.connect(dbURL, {
	reconnectTries: retryMaxAttempt,
	reconnectInterval: retryInterval
});

mongoose.connection.on('open', function(){
    console.log("Opened connection ", dbURL);
});
mongoose.connection.on('connected', function(){
    console.log("Connected connection ", dbURL);
});
mongoose.connection.on('error', function(err){
    if (err.message 
    	&& err.message.match(/failed to connect to server .* on first connect/)
    	&& retryCountFirstConnect < retryMaxAttempt) {
        console.log(new Date(), String(err));
        setTimeout(function () {
            console.log("Retrying first connect...");
            mongoose.connection.openUri(dbURL).catch(() => {});
        }, retryInterval);
        retryCountFirstConnect++;
    } else {
        console.error(new Date(), String(err));
    }
});
mongoose.connection.on('close', function() {
	console.log("Closed connection");
});
mongoose.connection.on('disconnected', function(){
    console.log("Disconnected");
});
mongoose.connection.on('reconnected', function(){
    console.log("Reconnected ", dbURL);
});

Taken from: Automattic/mongoose#5169 (comment)

Empty catch is required.