Nodejs and Twitter API 1 - res.on function

Question

Newb working through Node.js in 24 Hours. This challenge comes from Chapter 15 on JSON API's.

The original code:

var http = require('http')
    , data = ""
    , tweets = "";

var options = {
    protocol: 'http:'
    , host: 'search.twitter.com'
    , port: 80
    , path: '/search.json?q=%23node.js'
};

var request = http.get(options, function(res) {

    res.on('data', function(chunk){
        data += chunk;
    });
    res.on('end', function() {
        tweets = JSON.parse(data);
        console.log(tweets);
        for (var i= 0; i< tweets.results.length; i++) {
            console.log(tweets.results[i].text)
        }
    });
    res.on('errors', function(e){
        console.log("There was an error: " + e.message)
    });
});

My question concerns 'res.on(...)'. What I think this means is that when the Twitter server responds with a string, 'data', then perform the function. But I read through the Twitter API (v1 - https://dev.twitter.com/docs/api/1) and didn't see anything that supports that belief. So how exactly does res.on(...) work? TIA for any guidance.

Answer 1

res is a NodeJS event emitter, and res.on hooks up a callback for an event. The object res that you are using is a Node http response object, and it has nothing to do with the REST API that Twitter provides. The Node client makes a request to a http server (be it Twitter or Google or Stackoverflow). When the server responds, the res object emits the corresponding events.

You can try

, host: 'stackoverflow.com',
, port: 80,
, path: '/questions/18149079/nodejs-and-twitter-api-1-res-on-function'

and

res.on('end', function() {console.log(data)});

and check out the resulting html data :P