实现高阶函数combinedFetcher

function fetch(arg) { return response with: ${arg}; } function fetcher(arg, cb){ let res = fetch(arg); cb(res); } function combinedFetcher(...args) { const len = args.length; let cnt = 0; const res = []; function innerCB(r, cb) { cnt++; res.push(r) if(cnt === len) cb(res); }

return cb => args.forEach(arg => fetcher(arg, r => innerCB(r, cb))); }

const fetchFruitsAndDrinks = combinedFetcher("fruits", "drinks"); fetchFruitsAndDrinks(console.log)