How to get response headers when using needle.js in streaming mode?

Question

I want to use the needle module for node.js in streaming mode, similar to this example from the needle docs:

var stream = needle.get('http://www.as35662.net/100.log');

stream.on('readable', function() {
  var chunk;
  while (chunk = this.read()) {
    console.log('got data: ', chunk);
  }
});

This allows me to read the response body from the stream.

How can I access the response headers?

Answer 1

From reading the source, needle emits two events, header and headers.

Interested in headers only:

var stream = needle.get(someURL);

stream.on('headers', function(headers) {
    // do something with the headers
});

or status code and headers:

stream.on('header', function(statusCode, headers) {
    if (statusCode != 200) {
        // scream and panic
    }
});

Answer 2

You can read the header before stream starts if you want to.

var needle = require('needle');
var url = 'http://www.stackoverflow.com';

    needle.head(url, {method: 'HEAD'}, function (err, response) {
        if (!err && response.statusCode == 200) {
            console.log((JSON.stringify(response.headers)));
        }

    });

Or in Request

var request = require('request');
var url = 'http://www.stackoverflow.com';

request(url, {method: 'HEAD'}, function (err, response) {
    if (!err && response.statusCode == 200) {
        console.log((JSON.stringify(response.headers)));
    }    
});

Otherwise you can read it after stream.

var needle = require('needle');
var url = 'http://www.stackoverflow.com';

var stream = needle.get(url, function (err, response) {
    if (!err && response.statusCode == 200)
    console.log((JSON.stringify(response.headers)));
});

But this is also valid for request.

var request = require('request');
var url = 'http://www.stackoverflow.com';

var stream = request.get(url, function (err, response) {
    if (!err && response.statusCode == 200)
    console.log((JSON.stringify(response.headers)));
});