An example implementation of reduce with a stop function callable in iterator

stoppableReduceAsync.js

const stoppableReduce = (f, initialValue, collection, cb) => {
  const _collection = collection.slice();

  let stopper = false;

  const iterator = (acc, index, list) => {
    const item = list[index];
    
    const nextAcc = f(acc, item, () => {
      stopper = true;
    });

    if (stopper || index === (list.length - 1))
      return cb(nextAcc);

    return setImmediate(() => iterator(acc, index + 1, list));
  };


  iterator(initialValue, 0, collection);
};

stoppableReduce(
  (acc, item, stopAfterIteration) => {
    item >= 2 && stopAfterIteration();
    
    return [...acc, item+1 ]
  },
  [],
  [ 0, 1, 2, 3, 4 ],
  console.log
);

stoppableReduceSync.js

const stoppableReduce = (f, initialValue, collection) => {
  const _collection = collection.slice();

  let stopper = false;

  const iterator = (acc, index, list) => {
    const item = list[index];

    const nextAcc = f(acc, item, () => {
      stopper = true;
    });

    if (stopper || index === (list.length - 1))
      return nextAcc;

    return iterator(acc, index + 1, list);
  };


  const result = iterator(initialValue, 0, collection);

  return result;
};


console.log(stoppableReduce(
  (acc, item, stopAfterIteration) => {
    item >= 2 && stopAfterIteration();
    
    return [...acc, item+1 ]
  },
  [],
  [ 0, 1, 2, 3, 4 ]
));