如何使用多个函数对提取结果求和

我正在使用OpenWeatherMapAPI计算前5天的降水量总和。要做到这一点，我有5个异步函数，它们使用fetchapi调用api。我担心的是，收到的数据是24小时内每小时的历史天气数据下面的完整代码。json响应被存储到一个常量(例如const histData1(中，然后在该常量中迭代，以在给定的24小时内对所有一个值求和注意：湿度被用作概念证明，因为这里已经有一段时间没有下雨了

for (var i in histData1.hourly){
total1 += histData1.hourly[i].humidity;
};

当我将结果值total1发送到控制台时，我会收到预期的结果。当我试图将所有这些结果相加时，我遇到了麻烦，即total1+total2+total3+total4+total5。我认为一个可行的解决方案是返回每个函数的总[1，2，3，4，5]变量，然后求和。示例

var rainTotals = getData1() + getData2() + getData3() + getData4() + getData5()
console.log(rainTotals)

这导致了以下输出：[object Promise][object Promise][object Promise][object Promise][object Promise]，因此这似乎是一个数据类型问题。

有人能说明从五个单独的函数中添加所有湿度值吗。请随意吐槽我的代码，我对此还很陌生。

谢谢！

//WORKS Provies a json of hourly weather data for (1)24 hr period starting 5 days ago.
const fiveDaysAgo = Math.floor((Date.now() / 1000)-432000);
const fivedayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + fiveDaysAgo +"&appid="
async function getData5(){
const response5 = await fetch(fivedayURL)
const histData5 = await response5.json();
var total5 = 0
for (var i in histData5.hourly){
total5 += histData5.hourly[i].humidity;
};
console.log(total5);
return total5;
}
getData5();

const fourDaysAgo = Math.floor((Date.now() / 1000)-345600);
const fourdayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + fourDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData4(){
const response4 = await fetch(fourdayURL)
const histData4 = await response4.json();
var total4 = 0;
for (var i in histData4.hourly){
total4 += histData4.hourly[i].humidity
};
console.log(total4);
return total4;
}
getData4();

const threeDaysAgo = Math.floor((Date.now() / 1000)-259200);
const threedayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + threeDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData3(){
const response3 = await fetch(threedayURL);
const histData3 = await response3.json();
var total3 = 0;
for (var i in histData3.hourly){
total3 += histData3.hourly[i].humidity;
};
console.log(total3);
return total3;
}
getData3();
const twoDaysAgo = Math.floor((Date.now() / 1000)-172800);
const twodayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + twoDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData2(){
const response2 = await fetch(twodayURL);
const histData2 = await response2.json();
var total2 = 0;
for (var i in histData2.hourly){
total2 += histData2.hourly[i].humidity;
};
console.log(total2);
return total2;
}
getData2();
const oneDaysAgo = Math.floor((Date.now() / 1000)-86400);
const onedayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + oneDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData1(){
const response1 = await fetch(onedayURL);
const histData1 = await response1.json();
var total1 = 0;
for (var i in histData1.hourly){
total1 += histData1.hourly[i].humidity;
};
console.log(total1);
return total1;
}
getData1();
var rainTotals = getData1() + getData2() + getData3() + getData4() + getData5()
console.log(rainTotals)//returns [object Promise][object Promise][object Promise][object Promise][object Promise]

这里发生了一些事情。首先，为了回答您的问题，因为您的getDataX函数被声明为异步的，所以它们返回Promises，该Promises最终将使用您要查找的实际值进行解析或拒绝。

在使用Promises时，您需要在所有这些Promises都得到解决后求和总价值。

其次，您的代码中有一些重复。您会注意到，getDataX函数的内部结构之间几乎没有什么区别。为了简化这一点，您可以提取差异作为函数参数，并将所有相同的代码封装在一个函数中。

这将导致如下实现：

function getDaysAgo(days) {
return Math.floor((Date.now() / 1000) - (86400 * days))
}
async function getDataForDaysAgo(days) {
let daysAgo = getDaysAgo(days)
const apiURL = `http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=${daysAgo}&appid=5ffab1cda2c6b2750c78515f41421805`
const apiResponse = await fetch(apiURL)
const responseJson = await apiResponse.json()
var total = 0
responseJson.hourly.forEach(hour => {
total += hour.humidity
});
console.log(`getDataForDaysAgo(${days}) returns ${total}`)
return total
}
async function getDataSums() {
var data1 = await getDataForDaysAgo(5)
var data2 = await getDataForDaysAgo(4)
var data3 = await getDataForDaysAgo(3)
var data4 = await getDataForDaysAgo(2)
var data5 = await getDataForDaysAgo(1)
return data1 + data2 + data3 + data4 + data5;
}
getDataSums().then(result => {
console.log(result)
})

异步函数总是返回promise。

您可以使用Promise.all将它们聚合到一个数组中。

Promise.all([getData1(), getData2(), getData3(), getData4(), getData5()]).then((values) => {
var sum = 0;
for(var i=0; i<values.length; i++){
sum += values[i];
}
console.log(sum);
});

来源：异步函数

您可以使用await来获得async函数的结果。

var rainTotals = await getData1() + await getData2() + await getData3() + await getData4() + await getData5();

异步函数由于等待等待而延迟。'return‘立即给出数据，这就是为什么数据给出空对象(当console.log(getData1(((只返回空对象时(。因此，应该等待获得总数据每个getData函数中的total数据被推送到一个数组中。每个getData函数都在asyncAll函数中等待，以便一次记录数组。

// Data array
let arr = [];

//WORKS Provies a json of hourly weather data for (1)24 hr period starting 5 days ago.
const fiveDaysAgo = Math.floor((Date.now() / 1000)-432000);
const fivedayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + fiveDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData5(){
const response5 = await fetch(fivedayURL)
const histData5 = await response5.json();
var total5 = 0
for (var i in histData5.hourly){
total5 += histData5.hourly[i].humidity;
};
console.log(total5);
await arr.push(total5);
return total5;
}
getData5();

const fourDaysAgo = Math.floor((Date.now() / 1000)-345600);
const fourdayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + fourDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData4(){
const response4 = await fetch(fourdayURL)
const histData4 = await response4.json();
var total4 = 0;
for (var i in histData4.hourly){
total4 += histData4.hourly[i].humidity
};
console.log(total4);
await arr.push(total4);
return total4;
}
getData4();

const threeDaysAgo = Math.floor((Date.now() / 1000)-259200);
const threedayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + threeDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData3(){
const response3 = await fetch(threedayURL);
const histData3 = await response3.json();
var total3 = 0;
for (var i in histData3.hourly){
total3 += histData3.hourly[i].humidity;
};
console.log(total3);
await arr.push(total3);
return total3;
}
getData3();
const twoDaysAgo = Math.floor((Date.now() / 1000)-172800);
const twodayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + twoDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData2(){
const response2 = await fetch(twodayURL);
const histData2 = await response2.json();
var total2 = 0;
for (var i in histData2.hourly){
total2 += histData2.hourly[i].humidity;
};
console.log(total2);
await arr.push(total2);
return total2;
}
const oneDaysAgo = Math.floor((Date.now() / 1000)-86400);
const onedayURL = "http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=" + oneDaysAgo +"&appid=5ffab1cda2c6b2750c78515f41421805"
async function getData1(){
const response1 = await fetch(onedayURL);
const histData1 = await response1.json();
var total1 = 0;
for (var i in histData1.hourly){
total1 += histData1.hourly[i].humidity;
};
console.log(total1);

//Push data after data asynced 
await arr.push(total1);
return total1;
}
//Moved getData function to asyncAll function.
var rainTotals = [];

// Awaited for getData functions, logged total data.
async function asyncAll() {
await getData1();
await getData2();
await getData3();
await getData4();
await getData5();
await console.log(arr.join(', '), 'async');
}
asyncAll();

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