mongoose node.js reconnect code

reconnect-on-disconnect.js

var mongoose = require('mongoose');

var db = mongoose.connect("mongodb://localhost/testdb");
var reconnTimer = null;

function tryReconnect() {
  reconnTimer = null;
  console.log("try to connect: %d", mongoose.connection.readyState);
  db = mongoose.connect("mongodb://localhost/testdb");
}

mongoose.connection.on('opening', function() {
  console.log("reconnecting... %d", mongoose.connection.readyState);
});

mongoose.connection.on('open', function() {
  console.log("connected");
  if (reconnTimer) { clearTimeout(reconnTimer); reconnTimer = null; }
});

mongoose.connection.db.on('close', function() {
  console.log("disconnected");

  mongoose.connection.readyState = 0; // force...
  mongoose.connection.db.close(); // removeAllListeners("reconnect");

  if (reconnTimer) {
    console.log("already trying");
  }
  else {
    reconnTimer = setTimeout(tryReconnect, 500); // try after delay
  }
});


process.on('SIGINT', process.exit.bind(process));

setInterval(function() {
  console.log('alive: %d', mongoose.connection.readyState);
},2500);

@lauramorillo,
I am using setTimeout to continuously try to connect on disconnect.

ex:

1. Attach event handler
   instance.connection.on("disconnected", () => {
   console.log("Databse disconnected: ");
   if (connected) {
   connected = false;
   console.log("After disconnect");
   tryPersistentDbConnection(dbSettings, connectUrl, mongoose, { server: { auto_reconnect: false } });
   }
   });

private static tryPersistentDbConnection(dbSettings, connectUrl, mongoose, options) {
var instance = mongoose.connect(connectUrl, options, function (err) {
if (err) {
console.log("Error connecting. Error Message: " + err.message);
console.log("------------Trying to reconnect------------------");
setTimeout(function () {
//call itself on failure
tryPersistentDbConnection(dbSettings, connectUrl, mongoose, options)
}, 25000)
}
});
}