NodeJS write response to browser multiple times - node.js

Question

I have a simple nodeJS server that fetches data from another server and store them in a JSON files, i need to write a status about each file fetched and generated, but that doesn't work, because i have to execute response.end(), which implies that i can't write to the stream again, without ending the stream
here's my code:
var http = require('http');
var module = require('fs');
var APIs = [ '/servlet/en', '/servlet/fr' ];
var langs =[ 'en', 'fr' ];
var finish = false;
var host = 'http://www.localtest';
const port = process.argv[2] || 9000;
var responses = [];
http.createServer(function (req, response) {
for (x in APIs){
console.log(x);
var options = {
host: 'localtest',
port: 8888,
path: APIs[x],
lang: langs[x]
};
http.get(options, function(res) {
res.setEncoding('utf8');
var body='';
res.on('data', function(chunk){
body += chunk;
});
res.on('end', function(chunk){
responses.push(body);
if (responses.length == 2){
var d = JSON.parse(responses[1]);
var d2 = JSON.parse(responses[0]);
module.writeFileSync("options.lang1"+".json",JSON.stringify(d) , 'utf-8');
module.writeFileSync("options.lang2"+".json",JSON.stringify(d2) , 'utf-8');
}
});
});
}
}).listen(parseInt(port));
console.log(`Server listening on port ${port}`);
An example, i tried to write a message to the user after the line :
responses.push(body);
using response.write(), but this method needs an response.end() in order to be executed and displayed on the browser, If i do that i can't write to the stream anymore!

Answer 1

Couple issues with your code here. First off, you shouldn't use module as a variable, as that is a word that's already used in node's moduling system, e.g. in module.exports
Second, You really want to have some control flow in there. here's a complete example using the async library, though others prefer Promises.
var http = require('http');
var fs = require('fs');
var APIs = [ '/servlet/en', '/servlet/fr' ];
var langs =[ 'en', 'fr' ];
var host = 'http://www.localtest';
const port = process.argv[2] || 9000;
const async = require('async');
let responses = [];
function fetchAndWriteFile(lang, callback){
var options = {
host: 'localtest',
port: 8888,
path: '/servlet/'+lang,
lang: lang
};
http.get(options, function(res) {
res.setEncoding('utf8');
const filename = 'options.'+lang+'.json';
const fileStream = fs.createWriteStream(filename, {defaultEncoding: 'utf-8'});
fileStream.on('end', (e)=> {
if(e) return callback(e);
return callback(null, filename);
});
res.pipe(fileStream)
});
}
http.createServer(function (req, response) {
// this will run the fetchAndWriteFile once for each lang in langs
async.map(langs, fetchAndWriteFile, (e, files) => {
response.end(files); // files will be an array of filenames saved
});
}).listen(parseInt(port));
console.log(`Server listening on port ${port}`);