Using async with http.get, node js

Question

I have this array with rest-api paths:

var paths = ['path1','path2','path3'];

I want to create an array with results from each path. In this case I instead use 'http://www.google.com/index.html' instead of 'path'

exports.test = function(req, res){

  var paths = ['path1','path2','path3'];

  var resultArr = [];
  async.each(paths, function(path, cb){

    console.log('collecting data from: ' + path);
    http.get('http://www.google.com/index.html', function(result){

      resultArr.push(result);
      console.log('Done collecting data from: ' + path);
      cb();
    });

  }, function(){
    console.log('Done collecting data from all paths');
    res.status(200).send('hello');
  });
};

This logs:

Starting server at 127.0.0.1:5000
collecting data from: path1
collecting data from: path2
collecting data from: path3
Done collecting data from: path2
Done collecting data from: path1
Done collecting data from: path3
Done collecting data from all paths
GET /test 304 128.752 ms - -

It's not waiting for a a call to complete. I want to get the results in series, one by one. What am I doing wrong?

You code behave correctly, what are you expecting to happen here ? — Cyrbil
– Cyrbil, Commented Dec 6, 2015 at 14:56
"Note, that since this function applies iterator to each item in parallel, there is no guarantee that the iterator functions will complete in order." - npmjs.com/package/async#each — TAGraves
– TAGraves, Commented Dec 6, 2015 at 15:00

Mikko Johansson · Accepted Answer · 2015-12-06 15:08:30Z

2

Change each to eachSeries.

exports.test = function(req, res){

  var paths = ['path1','path2','path3'];

  var resultArr = [];
  async.eachSeries(paths, function(path, cb){

    console.log('collecting data from: ' + path);
    http.get('http://www.google.com/index.html', function(result){

      resultArr.push(result);
      console.log('Done collecting data from: ' + path);
      cb();
    });

  }, function(){
    console.log('Done collecting data from all paths');
    res.status(200).send('hello');
  });
};

This logs:

collecting data from: path1
Done collecting data from: path1
collecting data from: path2
Done collecting data from: path2
collecting data from: path3
Done collecting data from: path3
Done collecting data from all paths

answered Dec 6, 2015 at 15:08

Mikko Johansson

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