javascript - 具有 Node.js 异步的 API 数据并检索数据使其同步

Question

我需要有关我正在制作的 Node 天气应用程序的帮助。我使用 Google API 获取地址的经度和纬度，并将其输入到 Dark Sky API 中，以 JSON 格式返回天气。

我的问题是，大多数时候天气 API 都会在 google API 返回经度和纬度之前进行搜索。我知道为什么这样做是因为 Node.js 的异步特性。我的问题是如何使这部分同步？

var express = require('express');
var https = require('https')
var bodyParser = require("body-parser");

var app = express();

app.use(bodyParser.urlencoded({
extended: true
}));

app.use(bodyParser.json());

var lon;

var lat;

app.post('/', function(req,res,next){

var search = req.body.search;


function google(){

    var api = "API-KEY";

    var url = https.get(`https://maps.googleapis.com/maps/api/geocode/json?address=${search}&key=${api}`, function(res3){

        var body = "";
        var googleResults;

        res3.on('data', function(data){
            body += data.toString();
        })

        res3.on('end', function(){

            googleResults = JSON.parse(body);
            //console.log(body);
            lat = googleResults.results[0].geometry.location.lat;
            lon = googleResults.results[0].geometry.location.lon;
            console.log(search);
        })

    });

}


google();

//connectc to API URL()
var request = https.get(`https://api.darksky.net/forecast/API-KEY/${lon},${lat}`, function(res2){

console.log(lon + " " + lat)
            var body = "";
            var weather;
            //Read the data
            res2.on('data', function(data){
                body += data.toString();

            })

            res2.on('end', function(){
                    //Parse the data
                     weather = JSON.parse(body);
                    //Print data
                    //console.log("test = " + weather.currently.temperature)
                    res.render('index', {
                        temperature: weather.currently.temperature,
                        humidity: weather.currently.humidity,
                        wind: weather.currently.windSpeed
                    });
            })

});



});

Answer 1

最简单的事情是让 google() 将回调函数作为参数，而无需过多地重构代码。然后您可以使用该回调函数来触发对黑暗天空的调用。

var express = require('express');
var https = require('https')
var bodyParser = require("body-parser");

var app = express();

app.use(bodyParser.urlencoded({
  extended: true
}));

app.use(bodyParser.json());

app.post('/', function(req, res, next) {

  var search = req.body.search;

  // Have google() take a callback function as an argument and
  // call that function with the data when it's done.
  function google(cb) {

    var api = "API-KEY";

    var url = https.get(`https://maps.googleapis.com/maps/api/geocode/json?address=${search}&key=${api}`, function(res3) {

      var body = "";
      var googleResults;

      res3.on('data', function(data) {
        body += data.toString();
      })

      res3.on('end', function() {

        googleResults = JSON.parse(body);
        //console.log(body);
        lat = googleResults.results[0].geometry.location.lat;
        lon = googleResults.results[0].geometry.location.lon;
        // Call the function here
        cb(lat, lon);
      })

    });

  }

  // Now use the callback to do your second request to darksky
  google(function(lat, lon) {
    //connectc to API URL()
    var request = https.get(`https://api.darksky.net/forecast/API-KEY/${lon},${lat}`, function(res2) {

      console.log(lon + " " + lat)
      var body = "";
      var weather;
      //Read the data
      res2.on('data', function(data) {
        body += data.toString();

      })

      res2.on('end', function() {
        //Parse the data
        weather = JSON.parse(body);
        //Print data
        //console.log("test = " + weather.currently.temperature)
        res.render('index', {
          temperature: weather.currently.temperature,
          humidity: weather.currently.humidity,
          wind: weather.currently.windSpeed
        });
      })

    });
  }});


});