写一下我对后面两个手撕的思路： 第一题： function muiltiRequest(urls,maxNum) {     return new Promise((resolve,rejcet) => {         let cur = 0,finished = 0,res = [],_urls = [...urls];         function add() {             if(_urls.length !== 0 && cur < maxNum) {                 cur++;                 let temp = _urls.shift();                 axious.get(temp).then((data) => {                     res[urls.indexOf(temp)] = data;                     finished++;                     if(finished === urls.length) {                         resolve(res);                     }                     cur--;                     if(cur < maxNum) {                         add();                     }                 })                 .catch((err) => {                     rejcet(err);                 });                 add();             }         }         add();     }); }