Maybe the samllest flux implementation ever

genux.js

//utilitary functions
const find = (pred, coll) => {
  for(const item of coll){
    if(pred(item)){
      return item;
    }
  }
  return null;
};

const actionTypeIs = (actionType) => {
  return (handlerDesc) => { return handlerDesc[0] === actionType; }
};
//flux container
var g = function*(initialState, handlers){
  let store = initialState;
  while(true){
    const {actionType, payload} = yield store;
    const handlerDesc = find(actionTypeIs(actionType), handlers);
    if (!handlerDesc) {
      throw `[ERROR] No handlers is registred for this action type ${actionType}`;
    }
    store = handlerDesc[1](store, payload);
  }
}
//reducers
const inc = (state, payload) => { return state + 1; }
const dec = (state, payload) => { return state - 1; }

//instantiation of the genux container
var gen = g(0, [["inc", inc], ["dec", dec]]);
gen.next();

// usage of the container
console.log(gen.next({actionType:"inc"})); //{ value: 0, done: false }
console.log(gen.next({actionType:"inc"})); //{ value: 1, done: false }
console.log(gen.next({actionType:"inc"})); //{ value: 2, done: false }
console.log(gen.next({actionType:"dec"})); //{ value: 1, done: false }
console.log(gen.next({actionType:"dev"})); //thow [ERROR] No handlers is registred for this action type dev

//run with
//babe-node genux.js