Promise throttling using a generator

throttle-promises.js

function throttlePromises(elements, asyncForEach, groupSize){
  return new Promise(function(resolve, reject){
    //create a generator object that 'yields' for every group
    const genObj = function* gen(){
      while(elements.length > 0){
        yield Promise.all(elements.splice(0, groupSize).map(asyncForEach))
          .then(() => genObj.next());
      }
      return resolve(true);
    }();
    genObj.next();
  })
}

//example
const concurrentRequests = 2; 
const divIds = ['dog', 'cat', 'donkey', 'pig', 'chicken', 'coatimundi'];

const loadImage = function(x){
  //dome something async with x
 return load(x.jpg);
}

throttlePromises(divIds, loadImage, concurrentRequests);