如何避免帶有承諾的代碼中的拖尾回調

Question

我有一個嵌套回調的代碼塊。我對代碼重構感興趣，以使其更具可讀性並避免代碼膨脹。有人可以提及如何將下面的代碼轉換爲承諾。我希望做一個比較，看看它的價值延伸跨越這樣的代碼回調實現

dataApi.getClientEntityByCtnId(Number(key), function (error, client1) { 
    if (error) return callback(error, null); 
    if (client1.id == 0) 
     return callback("unregistered client:"+ key, null); 
    dataApi.getClientEntityByCtnId(Number(key2), function (error, client2) { 
     if (error) 
      return callback(error, null); 
     if (client2.id == 0) 
      return callback("unregistered client:" + key2, null); 

     dataApi.setClientRelationshipEntity(client1.id, client2.id, function (error) { 
      if (error) return callback(error, null);       
      dataApi.setClientRelationshipEntity(client2.id, client1.id, function (error) { 
       nbCRpushed++; 
       if (nbCRpushed%1000==0) dataApi.logger.info("nb CR pushed into BC ="+nbCRpushed+"/" + dataApi.nbCR); 
       if (error) return callback(error, null); 

       if (nbCRpushed == dataApi.nbCR) 
       { 
        dataApi.pushCRToCache(callback); 
       } 
      }); 
     }); 
    }); 
}); 

Answer 1

更看中的代碼將承諾的努力異步/等待：

async function optimised(){ 
    var client1 = await dataApi.getClientEntityByCtnId(+key); 
    if (client1.id == 0) 
    throw new Error("unregistered client:"+ key); 
var client2 = await dataApi.getClientEntityByCtnId(+key2); 
if (client2.id == 0) 
    throw new Error("unregistered client:" + key2); 

await dataApi.setClientRelationshipEntity(client1.id, client2.id); 
await dataApi.setClientRelationshipEntity(client2.id, client1.id); 

//i think the code below is broken now... more info needed to make it work asyncly 
nbCRpushed++; 
if (nbCRpushed%1000==0) dataApi.logger.info("nb CR pushed into BC ="+nbCRpushed+"/" + dataApi.nbCR); 
if (nbCRpushed == dataApi.nbCR){ 
       dataApi.pushCRToCache(callback);//um callback? what should we do here?? 
} 
} 

可用像這樣的：

optimised().then(function(){ 
    console.log("sucess"); 
},function(error){ 
    console.error(error); 
}); 

注意，所有dataApi方法需要返回的承諾，使這項工作...