How to get data out of a Node.js http get request

问题:

I'm trying to get my function to return the http get request, however, whatever I do it seems to get lost in the ?scope?. I'm quit new to Node.js so any help would be appreciated

function getData(){
  var http = require('http');
  var str = '';

  var options = {
        host: 'www.random.org',
        path: '/integers/?num=1&min=1&max=10&col=1&base=10&format=plain&rnd=new'
  };

  callback = function(response) {

        response.on('data', function (chunk) {
              str += chunk;
        });

        response.on('end', function () {
              console.log(str);
        });

        //return str;
  }

  var req = http.request(options, callback).end();

  // These just return undefined and empty
  console.log(req.data);
  console.log(str);
}

回答1:

Of course your logs return undefined : you log before the request is done. The problem isn't scope but asynchronicity.

http.request is asynchronous, that's why it takes a callback as parameter. Do what you have to do in the callback (the one you pass to response.end):

callback = function(response) {

  response.on('data', function (chunk) {
    str += chunk;
  });

  response.on('end', function () {
    console.log(req.data);
    console.log(str);
    // your code here if you want to use the results !
  });
}

var req = http.request(options, callback).end();

回答2:

Shorter example using http.get:

require('http').get('http://httpbin.org/ip', (res) => {
    res.setEncoding('utf8');
    res.on('data', function (body) {
        console.log(body);
    });
});

回答3:

from learnyounode:

var http = require('http')  

http.get(options, function (response) {  
  response.setEncoding('utf8')  
  response.on('data', console.log)  
  response.on('error', console.error)  
})

'options' is the host/path variable

回答4:

from learnyounode:

var http = require('http')
     var bl = require('bl')

     http.get(process.argv[2], function (response) {
       response.pipe(bl(function (err, data) {
         if (err)
           return console.error(err)
         data = data.toString()
         console.log(data)
       }))
     })

回答5:

This is my solution, although for sure you can use a lot of modules that give you the object as a promise or similar. Anyway, you were missing another callback

function getData(callbackData){
  var http = require('http');
  var str = '';

  var options = {
        host: 'www.random.org',
        path: '/integers/?num=1&min=1&max=10&col=1&base=10&format=plain&rnd=new'
  };

  callback = function(response) {

        response.on('data', function (chunk) {
              str += chunk;
        });

        response.on('end', function () {
              console.log(str);
          callbackData(str);
        });

        //return str;
  }

  var req = http.request(options, callback).end();

  // These just return undefined and empty
  console.log(req.data);
  console.log(str);
}

somewhere else

getData(function(data){
// YOUR CODE HERE!!!
})