Node.js / Javascript-等待方法完成

Question

我在寫一個蒸汽交易機器人，但是我的問題是for循環不等到for循環內部的方法完成。 因此，代碼無法正常工作。

for (i = 0; i < offer.itemsToReceive.length; i++) {

    console.log(offer.itemsToReceive[i].market_hash_name);

    community.getMarketItem(appid.CSGO, offer.itemsToReceive[i].market_hash_name, function(err, items) {
        if (err) {
            Winston.error("Error getting Marketprice");
        } else {
            var cacheItemPrice = items.lowestPrice;
            totalValue += items.lowestPrice;
            Winston.info("Item " + offer.itemsToReceive[i].market_hash_name + " is " + items.lowestPrice + " Cents worth");
            if (items.lowestPrice <= minValue) {
                minValue = items.lowestPrice;
            }
        }

    });
}

如果循環不等到方法完成，則變量i在該方法中不正確，並且得到錯誤的結果。

編輯 ：
現在，當我將@Cleiton中的代碼放入要從中返回兩個值的函數中時，該函數將在方法有時間更改它們之前返回該值。

function checkItemPricesCashIn(offer) {
    Winston.info("Getting itemprices from trade #" + offer.id);
    var totalValue = 0;
    var minValue = 50;

    var executionList = [];

    function getMarketItem(item) {
        var market_hash_name = item.market_hash_name;
        return function() {
            community.getMarketItem(appid.CSGO, market_hash_name, function(err, items) {
                if (err) {
                    Winston.error("Error getting Marketprice");
                } else {
                    var cacheItemPrice = items.lowestPrice;
                    totalValue += items.lowestPrice;
                    Winston.info("Item " + market_hash_name + " is " + items.lowestPrice + " Cents worth");
                    if (items.lowestPrice <= minValue) {
                        minValue = items.lowestPrice;
                    }
                } 
                (executionList.shift() || function() {})();
            });
        }
    }

    offer.itemsToReceive.forEach(function(item) {
        executionList.push(getMarketItem(item));
    });

    if (executionList.length) {
        executionList.shift()();
    }

    console.log(totalValue);
    console.log(minValue);

    return {
        totalValue: totalValue,
        minValue: minValue
    }
}

Answer 1

您可以將某些庫用作異步https://github.com/caolan/async 。 與之相關的任何異步周期（每個系列或每個系列）。

 async.each(array, function(item, callback){ // do something with a item // call callback when finished callback(); }); 

Answer 2

以下是完整的工作代碼，希望對您有所幫助：）

 function checkItemPricesCashIn(offer, cb) { Winston.info("Getting itemprices from trade #" + offer.id); var totalValue = 0; var minValue = 50; var executionList = []; function getMarketItem(item) { var market_hash_name = item.market_hash_name; return function() { community.getMarketItem(appid.CSGO, market_hash_name, function(err, items) { if (err) { Winston.error("Error getting Marketprice"); } else { var cacheItemPrice = items.lowestPrice; totalValue += items.lowestPrice; Winston.info("Item " + market_hash_name + " is " + items.lowestPrice + " Cents worth"); if (items.lowestPrice <= minValue) { minValue = items.lowestPrice; } } (executionList.shift() || cb)(minValue,totalValue); }); } } offer.itemsToReceive.forEach(function(item) { executionList.push(getMarketItem(item)); }); if (executionList.length) { executionList.shift()(); } } 

如何使用：

checkItemPricesCashIn(yourOffer/*your offer*/, function(min, max){
//it will be execute just after
console.log('min', min);
console.log('max', max);

});