我正在写蒸汽机器人来计算已发送物品的价格。我无法正确使用功能。我想从URL获得价格,然后将其添加到console.log中。异步JavaScript和功能
我不能这样做,因为console.log在循环之前执行。
我真的很新的JavaScript,我不能修复:(
var whole_price = 0;
for(var i=0 ; i<offer.itemsToReceive.length; i++){
getPrice(offer.itemsToReceive[i].market_hash_name, function(price){
whole_price += price;
});
}
console.log('Accepted offer from ' + offer.partner + ' with ' + offer.itemsToReceive.length + ' items valued as '+whole_price+'$.');
功能得到了URL价格:
function getPrice(name, callback){
name = name.replace(/\ +/g, '%20');
var url = 'http://steamcommunity.com/market/priceoverview/?currency=1&appid=730&market_hash_name='+name;
var price = 0;
request(url ,function(error, res, body){
var useCSGOBACKPACK = false;
if(!error && res.statusCode == 200){
body = JSON.parse(body);
if(body.success == true){
price = body.median_price.substr(1);
}else{
useCSGOBACKPACK = true;
}
}else{
useCSGOBACKPACK = true;
}
if(useCSGOBACKPACK==true){
url = 'http://csgobackpack.net/api/GetItemPrice/?id='+name+'¤cy=USD';
request(url, function(error, res, body){
body = JSON.parse(body);
price = body.median_price;
});
}
callback(price);
});
}
'whole_price变量不能在回调里访问'为什么? – Cristy
哇,我修改了代码,它可以(可能之前,我没有错字),但仍然console.log执行循环之前。 – irqize
这是因为'getPrice'函数是异步的。您必须计算已完成的回调数,并且只在count = offer.itemsToReceive.length时记录该值。或者您可以使用'async'库或某个承诺库并等待所有回调。 https://github.com/caolan/async – Cristy