importAll 引入所有文件

/******** importAll.js *********/
let cache = {};

export default function importAll(r){
    r.keys().forEach(key => cache[key] = r(key));
    return cache;
}

/******** 使用 *********/
const cache1 = importAll(require.context('../assets/img1', true, /\.png|\.jpg));
const cache2 = importAll(require.context('../assets/img2', true, /\.png|\.jpg));
const cache = Object.assign(cache1, cache2);

let imgArr = [];
for(const key in cache){
    if(cache.hasOwnProperty(key)){
        imgArr.push(cache[key]);
    }
}