如何鏈接異步和非異步函數

Question

我有一個同步函數，它調用另一個包含異步調用的同步函數。 如下所示：

func alpha(){
   beta(); //sync
   charlie(); //sync but contains an async call
   delta(); // want this to only run after charlie() is done.
}

func charlie(){
   // do some stuff

   //Make async call
   firebase.database.ref.once().then( () =>{
       // Do some async stuff
       // Only after this stuff is done do I want Charlie() to run
   });  

}

更改 Alpha() 以便查理只在 Beta 之后運行的最佳方法是什么？

我想這樣做：

async func alpha(){
   beta(); //sync
   await charlie()
   delta();
}

func charlie(){
   return new Promise( (resolve,reject) => {
   // do some stuff

   //Make async call
   firebase.database.ref.once().then( () =>{
       // Do some async stuff
       setReactHook1(my_data); //react hook state update
       // Only after this stuff is done do I want Charlie() to run
       resolve();
   });  
 });
}

func delta(){
  if(some condition that only applies somtimes){
     setReactHook1(new_data); //overwrite the data that Charlie stored.
   }
}

就其價值而言，我正在使用 React，並且charlie()進行useState更新，我想確保delta()僅在useState完成后運行，我認為您無法用 Hooks 保證這一點。

Answer 1

async func alpha(){
   beta(); //sync
   await charlie(); //sync but contains an async call
   delta(); // now this will only run after charlie() is done
}
func charlie(){
   // do some stuff

   //Make async call and return promise 
   return firebase.database.ref.once()

 }

charlie()應該返回一個 promise， await會等到charlie()完成。