const datas = idList

  .map(id => url+'/id')

  .map(url => fetch(url).then(res => res.json()));

const p = new Promise.all(datas)

  .then(data => {...})

const datas = idList

  .map(id => url+'/id')

  .map(url => fetch(url).then(res => res.json()));

const foo = await Promise.all(datas);

const series = foo.map(data => {...})