如果我在 my app 中输入股票“goog”日志是:

responseStock = 
stockPrice = 1193.9900
updateStockPrice was a success
[ { stock: 'GOOG', price: '1193.9900', likes: 0 } ]

我已经阅读了很多很多关于 async/await(和 Promises)的文章，包括在 stackoverflow.com 上，并在 freeCodeCamp 论坛上提出了这个问题，但没有得到回应或已经能够弄清楚。我已经尝试了很多代码变体，但未能解决异步问题。我现在的位置是在所有函数上放置 await/async，但它不起作用。

app.route('/api/stock-prices')
    .get(function (req, res){
    var stock1 = req.query.stock1.toUpperCase();
    var stock2; //if stock2 compare stock prices
    if (req.query.stock2) { stock2 = req.query.stock2.toUpperCase();}
    var like = req.query.like ? 1 : 0;
    //console.log("like " + like)
    var ip = like ? req.ip : null;
    //console.log("ip is " + ip);
    var stockPrice;
    var responseStock = [];

    var sendResponse = async (response) => {
      if (response.lenght > 1) { //user entered 2 stocks to compare
        var likes0 = response[0].likes - response[1].likes; //compare relative likes
        var likes1 = response[1].likes - response[0].likes;
        await res.json({"stockData": [{"stock": response[0].stock, "price": response[0].price, "rel_likes": likes0},
                               {"stock": response[1].stock, "price": response[1].price, "rel_likes": likes1}]});
      } else {
        console.log("responseStock = " + response);
        await res.json({"stockData": response});

      };
    };

    var addNewStock = async (stock) => {
      var newStock = await new Stock({stock: stock, price: stockPrice, likes: like});
      console.log(newStock);
      newStock.save( (err, doc) => {
        if (err) { console.log(err); }
        else if (!doc) { console.log("addNewStock failed")} 
        else {
          console.log("addNewStock was a success"); 
          responseStock.push({"stock": doc.stock, "price": doc.price, "likes": doc.likes});
          console.log(responseStock);
        }
      });
    };

    var updateStockPriceAndLikes = async (stock) => {
      await Stock.findOneAndUpdate({stock: stock}, {price: stockPrice, $inc: {likes: like}, $push: {ip: ip}},
                             {new: true}, function(err, doc) {
        if (err) { console.log(err); }
        else if (!doc) { console.log("updateStockPriceAndLikes failed"); }
        else { 
          console.log("updateStockPriceAndLikes was a success"); 
          responseStock.push({"stock": doc.stock, "price": doc.price, "likes": doc.likes});
          console.log(responseStock);
        }
      })
    };

    var updateStockPrice = async (stock) => {
      console.log("stockPrice = " + stockPrice)
      await Stock.findOneAndUpdate({stock: stock}, {price: stockPrice},
                             {new: true}, async function(err, doc) {
        if (err) { console.log(err); }
        else if (!doc) { console.log("updateStockPrice failed"); }
        else { 
          console.log("updateStockPrice was a success");
          responseStock.push({"stock": doc.stock, "price": doc.price, "likes": doc.likes});
          console.log(responseStock);
        }
      })
    };

    var handleStock = async (stock) => {
      if (stock) {
       if (ip) {   // like is checked
       await Stock.findOne({stock: stock}, async function(err, doc) {
          if (err) { console.log(err); }
          else if (!doc) { 
           await  addNewStock(stock); //not in db, add new
          } else if (doc.ip.indexOf(ip) < 0) {  //ip not found
            await updateStockPriceAndLikes(stock);   //and push ip to db
          } else {
            await updateStockPrice(stock);
          }
        })
       } else if (!ip) {   //like is not checked
        await Stock.findOne({stock: stock}, async function(err, doc) {
          if (err) { console.log(err); }
          else if (!doc) {
            await addNewStock(stock);
          } else {
            await updateStockPrice(stock);
          }
        });
      }
    };
  };

    var getStockPrice = async (stock) => {  
      var url = "https://www.alphavantage.co/query?function=GLOBAL_QUOTE&symbol="
                + stock + "&apikey=" + process.env.ALPHA_API_KEY;
        await request(url, {json: true}, async function(err, resp, body) {
        if (err) { console.log(err); }
          else if (!body["Global Quote"]["05. price"]) {
            await res.send("please enter a valid stock");
          }
        else {
          //console.log("stockPrice = " + body["Global Quote"]["05. price"]); //correctly logs stock price
          stockPrice = body["Global Quote"]["05. price"];
          await handleStock(stock);
        } 
      })
    };

    var begin = async () => {  
      await getStockPrice(stock1);
      if (stock2) {
        await getStockPrice(stock2);
      }  
      await sendResponse(responseStock);
    };

    begin();
    /*responseStock = [ { stock: 'GOOG', price: '1250.4100', likes: 0 },
  { stock: 'MSFT', price: '141.3400', likes: 0 } ]*/


    });

我希望日志是

stockPrice = 1193.9900
updateStockPrice was a success
[ { stock: 'GOOG', price: '1193.9900', likes: 0 } ]
responseStock = [{ stock: 'GOOG', price: '1193.9900', likes: 0 }]

看来，我有一个我无法弄清楚的异步问题。

最佳答案

正如@jfriend00 在评论中提到的，await 不会在不返回 promise 的函数上工作。因此，我需要使用 await 的函数必须更改为返回一个 promise。

因此，例如，这不起作用:

var getStockPrice = (stock) => {  
  //request data from API
};

var begin = async () => {  
  await getStockPrice(stock1);
  if (stock2) { await getStockPrice(stock2); }  
  sendResponse(responseStock);
};

begin();

但这确实有效:

var getStockPrice = (stock) => {  
    return new Promise( (resolve, reject) => { 
      //Request data from API
      resolve();
    })   
};

var begin = async () => {  
  await getStockPrice(stock1);
  if (stock2) { await getStockPrice(stock2); }  
  sendResponse(responseStock);
};

begin();

关于javascript - 我的作业项目 : Stock Price Checker 的异步/等待问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57343398/