Node Callback array undefined (empty value)

Question

I im using node js to pass data from watcher every few seconds to function streamplay that stores id.ts filenames in array this works fine as it stores but when i callback from another function in my program i get undefined value from this array....and i can't figure out how it needs to be written:

var stream_play = [];

watch('/tmp/1_.m3u8', function(event, name) {
    /* DEFINE - variables */
    var ts    = [];
    ts.push(1);

    streamplay(id, ts[ts.length-1]);
});

function streamplay(id, ts, callback) {
   /* CHECH - ts */
   if (ts !== 0) {
      console.log('adding id..'+id+'...with ts...'+ts)
      stream_play[id] = ts;
   } else {
      return callback(stream_play[id]);
   }
}

And calling from main function in node like this:

 streamplay(stream, 0, function(response) {
       console.log('streaming ts file...'+response+'...to client...')                   
       res.write(fs.readFileSync('/tmp/'+response));
  })

I get this:

streaming ts file...undefined...to client...

Because stream_play array is empty

Maxim
– Maxim

2017-09-27 13:14:55 +00:00
Commented Sep 27, 2017 at 13:14 — Maxim
– Maxim, Commented Sep 27, 2017 at 13:14

Andy Gaskell · Accepted Answer · 2017-09-27 13:17:50Z

3

Your function call, streamplay(stream, 0, function(response) { will end up falling through to your else condition in streamplay. This line is return callback(stream_play[id]); and the stream_play array is initialized, but empty. Accessing a non-existent element in a JavaScript array returns undefined.

answered Sep 27, 2017 at 13:17

Andy Gaskell

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4 Comments

John Over a year ago

Yes i know that is empty but how to make array globally to make it to return value...i put variable outside function to make it globally but array is still empty

Andy Gaskell Over a year ago

One option would be to define stream_play like this: var stream_play = [0];

John Over a year ago

I added var stream_play = [0]; globally but it is sam undefined

John Over a year ago

No one have idea what it needs to done? Maybe using buffers? I read on node that buffer is global and is accessed throught whole node js application...i im using using ts fs.readfilesync...so maybe this can be done globally?

John · Accepted Answer · 2017-09-28 07:41:26Z

0

I found the solution and another problem...the first example using callback works now like charm. The problem was that i have master process and worker process and i read on node js site that master and worker process can't share between variables values...so the new question is how to share master and worker process variables so that i can access from all worker process variables values from master?

I im doing clustering with this because of my huge server load and cpu clustering is must to go.

answered Sep 28, 2017 at 7:41

John

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