assetAction.js

import {
  REQUEST_ASSET_BINARY,
  RECEIVE_ASSET_BINARY
} from './constants';

export const requestAssetBinary = (path) => ({
  type: REQUEST_ASSET_BINARY,
  path
});

export const receiveAssetBinary = (path, arrayBuffer) => ({
  type : RECEIVE_ASSET_BINARY,
  path,
  arrayBuffer,
});

export const fetchAssetBinary = (assetName) => (dispatch, getState) => {
  const state = getState();
  const assetPath = state.config.assetPath + '/' + assetName;

  if(!state.assets[assetName]){
    dispatch(requestAssetBinary(assetName));
    return fetch(assetPath)
      .then(response => response.arrayBuffer())
      .then(arrayBuffer => {
        dispatch(receiveAssetBinary(assetName, arrayBuffer))
        return arrayBuffer;
      });
  }
  
  return new Promise((resolve, reject) => {
    resolve(state.assets[assetName].arrayBuffer);
  });
};

assetReducer.js

import { handleActions } from 'redux-actions';

import {
  REQUEST_ASSET_BINARY,
  RECEIVE_ASSET_BINARY
} from './constants';

export const assetReducer = (state, action) => {
  switch (action.type) {
    case REQUEST_ASSET_BINARY:
      if(!state.assets[action.path]){
        state.assets[action.path] = {};
      }
      return state;
      break;
      
    case RECEIVE_ASSET_BINARY:
      state.assets = Object.assign({}, state.assets);
      state.assets[action.path].arrayBuffer = action.arrayBuffer;
      return Object.assign({}, state);
      break;
      
    default:
      return state;
  }
}

export default assetReducer;