制作多个api / http node.js请求的难度

Question

Hello I've gotten two api requests to work individually but I'm having a lot of trouble to get them both working on my node.js app. Is there an easy way to make two requests ? I've tried making two requests putting the data into a variable and then rendering both of them but I run into issues with global variables. Any help would be appreciated.

  request(url, function (err, response, body) {

    if(err){
      res.render('index', {weather: null, error: 'Error, please try again'});
    } else {
      let weather = JSON.parse(body);

      if(weather.main == undefined){
        res.render('index', {weather: null, error: 'Error, please try again'});
      } else {
        if (rain == "0,rain"){
        let weatherText = `It's ${weather.main.temp} degrees celsius and with wind speeds of ${weather.wind.speed} mph in ${weather.name} ${weather.sys.country}! & ${weather.weather[0].description}`  ;
        res.render('index', {weather: weatherText, error: null});
      }
      else{
        let weatherText = `It's ${weather.main.temp} degrees celsius and with wind speeds of ${weather.wind.speed} mph in ${weather.name} ${weather.sys.country}!`  ;
        res.render('index', {weather: weatherText, error: null});
      }
      }
    }

  });

request(url2, function (err, response, body) {
  if(err){
    res.render('index', {news: null, error: 'Error, please try again'});
  } else {
    let result = JSON.parse(body);
    let news = result.articles[0].title
    if(news == undefined){
      res.render('index', {news: null, error: 'Error, please try again'});
    } 
    else{

      res.render('index', {news:news, error: null});
    }
    }
  })

Answer 1

I would use a 'promise' to wait until a response has been received from your first request. Once this has happened, you can trigger your second request, (see 'then' on the link below). Once your second request returns a result, you can combine the response from both requests, before using the data.

If request B needs to use data from the response of request A, then request A should be first in the chain. This allows you to adjust your second request based on the response from the first eg with IF statements. If the two are completely independent, you can pick either request to go first.

There is a section on this link about chaining promises, which should be relevant to what you're trying to do: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

Details about error handling with promises and 'catch' https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch

Answer 2

There is no actual need to use promises, although they do simplify code structure, you can just a easily nest requests:

request(url, function(err, response, body) {
    request(url2, function(err2, response2, body2) {
        // Both request data is available here
    })
})

Note that the variable names used in the callback function can be changed here

Should you have a bunch of requests that can be ran independently, look into promise.all