Question

I’m not able to get my asynchronous code working with node.js

Trying both async and step libraries — the code only returns the first function (doesn’t seem to go through the rest). What am I doing wrong?

thanks!

var step = require('step');
step(
function f1(){
        console.log('test1');
},
function f2(){
        console.log('test2');
},
function finalize(err) {
    if (err) { console.log(err);return;}
    console.log('done with no problem');
  }
);

or THIS:

var async = require('async');
async.series([
function f1(){
        console.log('test1');
},
function f2(){
        console.log('test2');
},
function finalize(err) {
    if (err) { console.log(err);return;}
    console.log('done with no problem');
  }
]);

Answer 1

Step.js is expecting callbacks for each step. Also the function that is using Step should callback with the result and not return it.

So let’s say you have:

function pullData(id, callback){
  dataSource.retrieve(id, function(err, data){
    if(err) callback(err);
    else callback(data);
  });
}

Using Step would work like:

var step = require('step');

function getDataFromTwoSources(callback){
  var data1,
    data2;
  step(
    function pullData1(){
      console.log('test1');
      pullData(1, this);
    },
    function pullData2(err, data){
      if(err) throw err;
      data1 = data;
      console.log('test2');
      pullData(2, this);
    },
    function finalize(err, data) {
      if(err)
        callback(err);
      else {
        data2 = data;
        var finalList = [data1, data2];
        console.log('done with no problem');
        callback(null, finalList);
      }
    }
  );
};

This would get it to proceed through the steps.

Note that I personally prefer async for two reasons:

• Step catches all thrown errors and does a callback with them; this changes the behavior of the application, when these libraries should just be cleaning up the look of the code.
• Async has much better combination options and looks cleaner