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

I had to build something similar in a NodeJS-app some time ago. The way I did it was to first use the networkInterfaces() function is the OS-module and then check if one or more interfaces have a non-internal IP.

If that was true, then I used exec() to start ping with a well-defined server (I like Google's DNS servers). By checking the return value of exec(), I know if ping was sucessful or not. I adjusted the number of pings based on the interface type. Forking a process introduces some overhead, but since this test is not performed too frequently in my app, I can afford it. Also, by using ping and IP-adresses, you dont depend on DNS being configured. Here is an example:

var exec = require('child_process').exec, child;
child = exec('ping -c 1 128.39.36.96', function(error, stdout, stderr){
     if(error !== null)
          console.log("Not available")
      else
          console.log("Available")
});

Answer 2

Here is a one liner: (Node 10.6+)

let isConnected = !!await require('dns').promises.resolve('google.com').catch(()=>{});

Answer 3

As of 2019 you can use DNS promises lookup.

NOTE This API is experimental.

const dns = require('dns').promises;

exports.checkInternet = function checkInternet() {
    return dns.lookup('google.com')
        .then(() => true)
        .catch(() => false);
};

Answer 4

It is very helpful to check internet connection for our browser is available or not.

var internetAvailable = require("internet-available");

internetAvailable().then(function(){
    console.log("Internet available",internetAvailable);
}).catch(function(){
    console.log("No internet");
});

for more[internet-available][1]: https://www.npmjs.com/package/internet-available

Answer 5

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 6

It's a very simple function that does not import any stuff, but makes use of JS inbuilt function, and can only be executed when called, it does not monitor loss/internet connection; unlike some answers that make use of cache, this result is accurate as it does not return cached result.

const connected = fetch("https://google.com", {
    method: "FET",
    cache: "no-cache",
    headers: { "Content-Type": "application/json" },
    referrerPolicy: "no-referrer",
}).then(() => true)
  .catch(() => false);

call it using await(make sure your'e inside an async function or you'll get a promise)

console.log(await connected);