Iteration over an object and manipulating every node in a loop by adding new calculated content.

calculation in a "for loop"

        getProject(filteredSAV, metricPROJECT, function (distribution, mapped) {
          var keys = Object.keys(mapped);
          var tasksLeft = keys.length;

          function onComplete() {
            saveJSON("./tmp/", "project.json", mapped);
          }
          keys.forEach(function (subchar) {
            calcFrequencies(mapped[subchar], function (calculatedFrequencies) {
              mapped[subchar].analysis.stats = calculatedFrequencies;
              if (--tasksLeft === 0) {
                onComplete();
              }
            });
          });
        });

calcFrequencies() takes a while.

Is there a better way to write such a loop?

is this actually the answer:

async.forEach(Object.keys(dataObj), function (item, callback){
console.log(item); // print the key
callback(); // tell async that the iterator has completed

}, function(err) {
console.log('iterating done');
});

??