Promise Waterfall for dynamic number of promises with callback on each and array resolve on complete

dynamic-waterfall-promise.js

var counter = 0;
function run(cb) {
  counter++;
  return (function(count) {
    return new Promise(function(resolve, reject) {
        cb(count);
        resolve(count);
    });
  })(counter);
}


var promises = {
  onEach: function(fn){
    var testArray = ["1"];
    return testArray.reduce(function (acc) {
      return acc.then(function (res) {
        return boot(res, fn);
      });
    }, Promise.resolve([]));
  }
}

function boot(res, fn) {
  return run(fn).then(function(result) { // fetch from algolia
    res.push(result);
    if(result < 3) { // if cursor
      return boot(res, fn);
    }
    return res;
  })
}

promises
.onEach(function(count) {
  console.log('onEach', count);
})
.then(function(total) {
  console.log('total: ', total)
});