使用nodejs和socket.io将图像发送到客户端

Question

with the following code I'm able to send an Image to the client with socket.io, but I want also to send the size as a second argument. I would like to understand why the argument "size" is getting always undefined when I try to pass it to the socket.emit function. socket.emit('firstChunkSent', data, size) . Can you pls fix it ?

var io = require('../server').io

io.sockets.on('connection', function (socket) {

socket.on('imageRequest', function () {  

getTheNewImage(function(data,size){

socket.emit('firstChunkSent', data, size)

  }); 
 }); 
});

function getTheNewImage(callback){

var filename = 'image.gif';

var base64FileSize  = fs.stat(filename,function(err,stats){

if (err) { throw err; }

return stats.size

});

var readable = fs.createReadStream(filename, { encoding: 'base64' });

readable.on('readable', function() {

var getImageData = function(){

  while (null !== (base64ImageData = readable.read())) {

          return base64ImageData
          }
}
callback(getImageData(),base64FileSize)

});

readable.on('end', function() {

console.log('there will be no more data.')

});

readable.on('error', function(err) {

console.log('here is the error: '+err)

readable.end(err);

});

Answer 1

return stats.size

Need to use the callback

function getTheNewImage(callback){
    var filename = 'image.gif';
    var base64FileSize  = fs.stat(filename,function(err,stats){
    if (err) return callback(new Error(err));
    callback(null, stats.size)

});

getTheNewImage(function(data,size)

First param will be the error, not data