Where to define callback for async.series in node.js

Question

I want to have a callback called, when a async task is completed. Following is the code for the same:

var async = require("async");

function callMeWhenDone(err, result){
    if(err) console.log('Error Occurred');
    console.log('Callback called');
    console.dir(result);
}

function tasks() {
    console.log('Start executing tasks');
    var tasks = [];
    var result = {};

    tasks.push(function(callMeWhenDone) {
        console.log('Getting some data');
        callMeWhenDone(null, result);
    });
    tasks.push(function(callMeWhenDone) {
        console.log('Second function called');
        callMeWhenDone(null, result);
    });

    async.series(tasks, function(err, result){
        console.log('All done');
        callMeWhenDone(err, result);
    });
}

tasks();

In the code above, callMeWhenDone callback method is not getting called after a async task is completed.

How can i call it within the async task.

JohnnyHK · Accepted Answer · 2015-03-14 14:19:51Z

2

That's because you've given your async task callback parameter the same name of callMeWhenDone. Give that parameter a different name like cb and then call them both when each task is done:

function tasks() {
    console.log('Start executing tasks');
    var tasks = [];
    var result = {};

    tasks.push(function(cb) {
        console.log('Getting some data');
        callMeWhenDone(null, result);
        cb(null, result);

    });
    tasks.push(function(cb) {
        console.log('Second function called');
        callMeWhenDone(null, result);
        cb(null, result);
    });

    async.series(tasks, function(err, result){
        console.log('All done');
        callMeWhenDone(err, result);
    });
}

answered Mar 14, 2015 at 14:19

JohnnyHK

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