title: async.js - async.map does not return any value
body: <p>I have a problem when I am using the async library. 
  My aim is to be able to execute function requests in parallel, for this I am using the async library. In my code I am creating an array of functions which thebn has to be called in parallel using async.map. I have a problem when I want to read the return value from my async task.</p>
  
  <p>Here the code snippet:</p>
  
  <pre><code>  var pages = Math.ceil(rowCount/config.ROWS_PER_PAGE);
    var func = [];
    var top, left, wdith, height;
    for(var i=0; i&lt;=pages;i++) {
        top = i * config.ROWS_PER_PAGE;
        left = 0;
        width = config.DATA_PER_ROW;
        height = Math.min(config.ROWS_PER_PAGE, rowCount - i * config.ROWS_PER_PAGE); 
        var ff = makeCallbackFunc(top, left, width, height);
        func.push(ff(function () {return true;}));
     }
  
    async.map(
      func,
          function(err, results){  
              //???? Can not read the results output here!!??                        
              console.log('all calls called without any errors');
          });
  
    function makeCallbackFunc(top, left, width, height) {
      return function (callback) {
      console.log('top: ' + top + 'left: ' + left + 'width: ' + width + 'height: ' + height);
      return backendApi.getData([{
          qTop: top,
          qLeft: left,
          qWidth: width,
          qHeight: height
        }]);
  
      };
    }
  </code></pre>
  
  <p>This is the output using console.log(results);</p>
  
  <p><a href="https://i.stack.imgur.com/Nm57K.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Nm57K.png" alt="enter image description here"></a></p>
  
  <p>Thanks!</p>