index.js

import { LOAD_IMG, WALLPAPER_PATH_PREFIX } from '../../constants';

const imageLoaded = dispatch => e => dispatch({
  type: LOAD_IMG,
  payload: e.type === 'load'
});

export default function (url) {
  return (dispatch) => {
    const bigImg = new Image();
    const imageLoadedDispatch = imageLoaded(dispatch);
    
    bigImg.addEventListener('load', imageLoadedDispatch);
    bigImg.addEventListener('error', imageLoadedDispatch);
    
    bigImg.src = `${WALLPAPER_PATH_PREFIX}${url}`;
  };
}