How to make the backend communicate with the socket.io server

Question

I’m studying about socket. and I have a problem with the backend. I am developing a system that searches for files with certain extensions and shows them on a real-time screen.

To solve this I created a script by scanning all the files so that the same one to each file sends to my server this information. The problem is that I have already tried to connect these two files in several ways but could not. There is some way to do this?

Server.js

// Realiza o require do express, http, e socketio
var app = require('express')();
// passa o express para o http-server
var http = require('http').Server(app);
// passa o http-server par ao socketio
var io = require('socket.io')(http);

// cria uma rota para fornecer o arquivo index.html
app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

var name = "";
// sempre que o socketio receber uma conexão vai devoltar realizar o broadcast dela
io.on('connection', function(socket){
  socket.on('data_bind', msg => {
    console.log('data_bind');
    io.emit('data_bind', msg);
  })
});

// inicia o servidor na porta informada, no caso vamo iniciar na porta 3000
http.listen(3000, function(){
  console.log('Servidor rodando em: http://localhost:3000');
});

Index.html

   var socket = io();
socket.on('data_bind', msg => {
    let ul = document.getElementById("messages");
    let li = document.createElement('li');
    let br = document.createElement('br');
    li.appendChild(document.createTextNode(msg));
    ul.appendChild(li);

    document.getElementById('typing').innerHTML = "";
    document.getElementById('typing').hidden = true;
})

index js.

const testFolder = 'C://Users/user';
function Extension(tipo,quantidade){
    this.tipo = tipo;
    this.quantidade = quantidade;
}

var socket = require('socket.io')(3000)

var files  = [];

const fs = require('fs');
var quantidade = 0;

var dataAtual = new Date();
dataAtual = Date.parse(dataAtual);

function readDir(dir){

    let struct = {}

    fs
        .readdirSync(dir)
        .sort((a, b) => {
            try{
                fs.statSync(dir +"/"+ a).mtime.getTime() - fs.statSync(dir +"/"+ b).mtime.getTime()
            } catch(e){

            }
        }) 
        .forEach(file => {

            try{
                if( fs.lstatSync(dir+"/"+file).isFile() ){
                    struct[file] = null
                }
                else if( fs.lstatSync(dir+"/"+file).isDirectory() ){
                    struct[file] = readDir(dir+"/"+file)
                }

                var arquivo = file.split('.')
                var isNewFile = true;

                if(files.length == 0){
                    var arq = new Extension(arquivo[arquivo.length - 1], 1);
                    files.push(arq);
                } else {
                    files.forEach((valor,chave) => {
                        if(valor.tipo == arquivo[arquivo.length - 1]){
                            valor.quantidade = valor.quantidade + 1;
                            isNewFile = false; 
                        }
                    });

                    if(isNewFile){
                        var arq = new Extension(arquivo[arquivo.length - 1], 1);
                        files.push(arq);
                    }
                }


                var valor = dir + "/" + file + " date: " + fs.lstatSync(dir+"/"+file).mtime + " tipo: " + arquivo[1];
                quantidade++;
                var dataLimite = new Date('2019-06-08');
                var dataArquivo = new Date(fs.lstatSync(dir+"/"+file).mtime)

                if(Date.parse(dataLimite) < Date.parse(dataArquivo)){
                    valor += ": data posterior"
                } else {
                    valor += ": data inferior"
                }

                socket.emit('data_bind', valor);
                console.log(valor);
            } catch(e){
                return
            }   
        })

    return struct

}

readDir(testFolder);

If I try to send some information through the front end (creating an Emit) it enters the server normally, but nothing I send from the backend to the server runs.

Answer 1

In order for you to connect you need a client for the socket.io (https://www.npmjs.com/package/socket.io-client) this is a good option, in it you need to instantiate an object and point to the server url

Ex. const socket = io('http://localhost:3000');

then run the connection function:

socket.on('connect', event => {
   console.log(event)
})

On your server you will receive in the on Connection event an object containing the client id

Ex.

io.on('connect', socket => {
   console.log(socket.id)
})

The link I sent to download the socket.io-client has a good example of implementation.

In communication events have to listen on the server the same type of event.