任务队列的题可以用promise/async await来做 class Queue{     constructor(){         this.queue = [];     }     task(delay, callback){         this.queue.push({             delay,             callback         });         return this;     }     async start(){         for(let i=0;i<this.queue.length;i++){             await new Promise((resolve)=>{                 setTimeout(resolve, this.queue[i].delay)             }).then(()=>{                 this.queue[i].callback();             })         }     } }