Callback - error after 2nd callback

Question

I'm learning about callbacks and I wrote this code:

var http = require('http');
var str = "";
var count = 2;
function jugglingAsync(callback){
    http.get(process.argv[count], function(response){
        response.on("data", function(data){
            str+=data.toString();
        })
        response.on("end", function(){
            console.log(str);
            str = "";
            count++;
            if(count<5) callback();
        })
    })
}
jugglingAsync(jugglingAsync);

It should collect 3 URL adresses given as command-line arguments. Problem is - when first callback works fine and print good result, the second gives me an error:

            if(count<5) callback();
                        ^

TypeError: callback is not a function
    at IncomingMessage.<anonymous> (/home/dzikichrzan/Gdrive/Programowanie/JavaScript/learnyounode/jugglingAsync.js:13:16)
    at emitNone (events.js:73:20)
    at IncomingMessage.emit (events.js:167:7)
    at endReadableNT (_stream_readable.js:906:12)
    at nextTickCallbackWith2Args (node.js:455:9)
    at process._tickCallback (node.js:369:17)

Why this function works fine only one time?

If it says `callback` is not a function, what does it say that it **is**? `console.log` it. — Quentin, Dec 28 '15 at 21:56
looks like you would need to write `if (count<5) callback(callback);` — jcarpenter2, Dec 28 '15 at 22:00
At first time is shows 'callback' as 'undefined' and it crashes at second 'console.log'. — DzikiChrzan, Dec 28 '15 at 22:01

score 1 · Answer 1 · answered Dec 28 '15 at 22:04

1

You are calling jugglingAsync in

if(count<5) callback();

With no parameters, which is expecting a parameter as a callback function

answered Dec 28 '15 at 22:04

Nizar Ahmed

180
9

Right. So the first time through is no problem, but the second time has `callback` undefined. – Ted Hopp Dec 28 '15 at 22:15

Callback - error after 2nd callback

1 Answers1