代碼的承諾。於是承諾之前發射的方式完成

Question

我有這樣的代碼......對於混亂我一直在這一段時間遺憾：

loadAvailabilities() { 

    let promises = []; 
    let promises2 = []; 
    let indexi = 0; 
    //return new Promise((resolve, reject) => { 
     this.appointments = this.af.list('/appointments', { query: { 
     orderByChild: 'selected', 
     limitToFirst: 10 
     }}); 
     let mapped; 
     this.subscription2 = this.appointments.subscribe(items => items.forEach(item => { 
     //promises.push(new Promise((resolve, reject) => { 
      console.log(item); 
      let userName = item.$key; 
      //this.availabilities = []; 
      for(let x in item) { 
      let month = x; 
      console.log(x + "  month"); 

      this.appointmentsMonth = this.af.list('/appointments/' + userName + '/' + month); 
      this.subscription3 = this.appointmentsMonth.subscribe(items => items.forEach(item => { 
       this.startAtKeyAvail = item.$key; 
       //console.log(JSON.stringify(item) + "   item"); 
       let date = new Date(item.date.day * 1000); 
       let today = new Date(); 
       console.log(date.getMonth() + "==" + today.getMonth() + "&&" + date.getDate() + "==" + today.getDate()); 
       console.log("IN LOAD AVAILABILITIES *(*((**(*(*(*(*(*(*&^^^^%^%556565656565"); 
       if(date.getMonth() == today.getMonth() && date.getDate() == today.getDate()) { 
        console.log("   inside the if that checks if its today"); 
        console.log(item.reserved.appointment + "    *************appointment"); 
        //let counter = 0; 
        //mapped = item.reserved.appointment.map((r) => { 
        //item.reserved.appointment.forEach((r, index) => { 
        for(let r of item.reserved.appointment) { 
         promises.push(new Promise((resolve, reject) => { 
         if(r.selected == true) { 
          //this.renderer.setElementStyle(this.noavail.nativeElement, 'display', 'none'); 

          let storageRef = firebase.storage().ref().child('/settings/' + userName + '/profilepicture.png'); 

          let obj = {'pic':"", 'salon': userName, 'time': r.time}; 

          storageRef.getDownloadURL().then(url => { 
          console.log(url + "in download url !!!!!!!!!!!!!!!!!!!!!!!!"); 
          obj.pic = url; 
          this.availabilities.push(obj); 
          console.log(JSON.stringify(this.availabilities)); 
          resolve(); 
          }).catch((e) => { 
          console.log("in caught url !!!!!!!$$$$$$$!!"); 
          obj.pic = 'assets/blankprof.png'; 
          this.availabilities.push(obj); 
          console.log(JSON.stringify(this.availabilities)); 
          resolve(); 
          }); 
         } 
         })) 

        } 

       } 

       })) 
      } 
      })) 
      //})); 

      Promise.all(promises).then(() => { 
      console.log("in load availabilities ......... ") 
      console.log(JSON.stringify(this.availabilities)); 

      this.availabilities.sort(function(a,b) { 
       return Date.parse('01/01/2013 '+a.time) - Date.parse('01/01/2013 '+b.time); 
      }); 

      console.log('*****previous******'); 
      console.log(JSON.stringify(this.availabilities)); 
      console.log('*****sorted********'); 

      for(let i of this.availabilities) { 
       console.log(i.time + "   this is itime"); 
       let date = new Date('01/01/2013 ' + i.time); 
       console.log(date + "   this is date in idate"); 
       let str = date.toLocaleTimeString('en-US', { hour: 'numeric', hour12: true, minute: 'numeric' }); 
       console.log(str); 
       i.time = str; 
      } 
      }); 
     //})) 



    //}) 

    } 

我可以從日誌消息告訴了storageRef.getDownloadURL()函數發生在我的頁面加載結束時......這是對象實際被推到this.availabilities（最終用於填充列表）的地方。 Promise.all.then()中的代碼實際上在任何事件被推送到this.availabilities之前觸發，所以當發生排序時它是一個空數組，並且沒有任何排序。

Answer 1

我在每個forEach循環內使用了一個承諾。我把所有的承諾推到了相同的array，並且使用它如何在上面被使用 - 並且承諾完成了他們的工作 - 數組被排序，因爲一切都是異步發生的。