如何使用异步函数访问天气 API 雨数据

Question

我正在使用 OpenWeatherMap API 计算前 5 天的降水量总和。我在访问湿度或温度等值时没有问题，但在汇总前 5 天的所有降雨值时遇到问题。雨只有在物体反应时才有用，它是实际测量出来的。这是测量下雨时的样子的示例：

您可以看到每小时下雨。18.rain['1h']。我的问题是将它们全部加起来。

这是我的完整代码：

//converts current unix date from miliseconds to seconds and subtracts seconds from variable daysAgo
function getDaysAgo(days) {
    return Math.floor((Date.now() / 1000) - (86400 * days)) //returns date of privious 5 days from now.
}
//fetchs historic hourly weather data for rain.
async function getDataForDaysAgo(days) {
    let daysAgo = getDaysAgo(days) //nest getDaysAgo function to variable
    const apiURL = `http://api.openweathermap.org/data/2.5/onecall/timemachine?lat=29.8833&lon=-97.9414&dt=${daysAgo}&appid=` //calls historic weather api using privious days
    const apiResponse = await fetch(apiURL)  //fetch data
    const responseJson = await apiResponse.json() //converts data to json
    var total = 0
    console.log(responseJson);

    responseJson.hourly.forEach(hour => { //loops through each 1hr record of 24
          //if no rain is recorded, rain data is not available. system reprots: NaN
          if (isNaN(hour.rain['1h'])){
            hour.rain['1h'] = 0   //if rain is NaN, change that value to 0.
          }//else(total += hour.rain);
          else{
            total += hour.rain['1h']
          }//otherwise sum all available rain values.
          //total += hour.rain

    });
    console.log(`getDataForDaysAgo(${days}) returns ${total}`) //logs total rain values for each 24hr period
    return total
}
//call above fetch function with appropriate historic 'daysAgo'
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; //returns sum of 5 day rain values
}

getDataSums().then(result => { //waits for getDataSums and return result
    var totalRainInches = parseFloat((result)*25.4); //converts to mm to inches
      document.getElementById('precip5day').innerHTML = "Five Day Precipication Accumulation:"
      document.getElementById('precipValue').innerHTML = totalRainInches.toFixed(2) + "&Prime;"
    //proof of concept conditional statment that gives recommendations for trail use
    //based on 5 day rain totals and writes to index.html file
    if (totalRainInches <= 0.50){
      document.getElementById('conditions').innerHTML = "Hiking and mountain biking should be okay"
    } else if (totalRainInches < 3 ){
      document.getElementById('conditions').innerHTML = "Due to recent rain activity, use best judgement when hiking or mountain biking"
    } else if (totalRainInches > 7 ){
      document.getElementById('conditions').innerHTML = "Due to heavy rainfall, trails should not be used"
    }else {
      document.getElementById('conditions').innerHTML = "Something broke :("
    }
});

我很幸运将所有湿度值加在一起：

    responseJson.hourly.forEach(hour => {
         
          if (isNaN(hour.humidity)){
            hour.humidity = 0   
          }
          else{
            total += hour.humidity
          }

但是当谈到雨值时，我空手而归，并收到雨变量未定义的错误消息。任何想法？谢谢！另外，这里是 link 到让我走到这一步。

Answer 1

您确定 rain 从 0 点到 23 点的所有时间都存在吗？如果它丢失了，你会得到 "Uncaught TypeError: Cannot read property '1h' of undefined" 就像我下面的示例一样。如果你检查它，它应该总结得很好。

// prep 24 hours with rain and humidity
var hourly = []
for (let i = 0; i < 24; i++) {
  hourly[i] = {
    rain: {
      '1h': 0.5
    },
    humidity: 2.2
  }
}

// your code in a function
function sumRain(hourly) {
  var total = 0;
  hourly.forEach(hour => {
    // uncomment the next line to check for 'rain' being present
    // if (hour.rain)
    if (isNaN(hour.rain['1h'])) {
      hour.rain['1h'] = 0
    } else {
      total += hour.rain['1h']
    }
  });

  return total;
}

console.log(sumRain(hourly))

// modify hourly so rain is missing from one of the hours
delete hourly[11].rain;

// now sumrain throws an exception unless you check for hour.rain being present before trying to sum it up
console.log(sumRain(hourly))

如何使用异步函数访问天气 API 雨数据

How to access weather API rain data with async function

javascript

asynchronous

async-await

fetch-api

arcgis-js-api