Check for internet connectivity in NodeJs

Question

Installed NodeJS on Raspberry Pi, is there a way to check if the rPi is connected to the internet via NodeJs ?

Answer 1

A quick and dirty way is to check if Node can resolve www.google.com:

require('dns').resolve('www.google.com', function(err) {   if (err) {      console.log("No connection");   } else {      console.log("Connected");   } }); 

This isn't entire foolproof, since your RaspPi can be connected to the Internet yet unable to resolve www.google.com for some reason, and you might also want to check err.type to distinguish between 'unable to resolve' and 'cannot connect to a nameserver so the connection might be down').

Answer 2

While robertklep's solution works, it is far from being the best choice for this. It takes about 3 minutes for dns.resolve to timeout and give an error if you don't have an internet connection, while dns.lookup responds almost instantly with the error ENOTFOUND.

So I made this function:

function checkInternet(cb) {     require('dns').lookup('google.com',function(err) {         if (err && err.code == "ENOTFOUND") {             cb(false);         } else {             cb(true);         }     }) }  // example usage: checkInternet(function(isConnected) {     if (isConnected) {         // connected to the internet     } else {         // not connected to the internet     } }); 

This is by far the fastest way of checking for internet connectivity and it avoids all errors that are not related to internet connectivity.