Previously, we paid more attention to the front-end, but less attention to the back-end. However, I have always been interested in Node.js, and I went to CNODE exchange party in Ali last December.

I hope to share some notes about learning Node.js through my blog here in the future. On the one hand, I summarized my learning experience, on the other hand, I can share with you.

Well, that's probably what it is.

This article begins with a Node.js module called request. With this module, http requests become extremely simple.

Ultra simple to use

Request is extremely simple to use, while supporting https and redirection.

var request = require('request');
request('http://www.google.com', function (error, response, body) {
  if (!error && response.statusCode == 200) {
    console.log(body) // Print google Home Page
  }
})

flow

Any response can be output to the file stream.

request('http://google.com/doodle.png').pipe(fs.createWriteStream('doodle.png'))

Conversely, files can also be passed to PUT or POST requests. If header is not provided, the suffix name of the file is detected and the corresponding content-type is set in the PUT request.

fs.createReadStream('file.json').pipe(request.put('http://mysite.com/obj.json'))

Requests can also be pipe d to yourself. In this case, the original content-type and content-length will be retained.

request.get('http://google.com/img.png').pipe(request.put('http://mysite.com/img.png'))

form

request supports application/x-www-form-urlencoded and multipart/form-data for form upload.

x-www-form-urlencoded is simple:

request.post('http://service.com/upload', {form:{key:'value'}})

Or:

request.post('http://service.com/upload').form({key:'value'})

Using multipart/form-data, you don't have to worry about setting up header s or other trivial things, request s will help you solve them.

var r = request.post('http://service.com/upload')
var form = r.form()
form.append('my_field', 'my_value')
form.append('my_buffer', new Buffer([1, 2, 3]))
form.append('my_file', fs.createReadStream(path.join(__dirname, 'doodle.png'))
form.append('remote_file', request('http://google.com/doodle.png'))

HTTP authentication

request.get('http://some.server.com/').auth('username', 'password', false);

or

request.get('http://some.server.com/', {
  'auth': {
    'user': 'username',
    'pass': 'password',
    'sendImmediately': false
  }
});

Send Immediately, which defaults to true, sends a basic authentication header. When set to false, the server receives 401 and retries (the server 401 response must contain the WWW-Authenticate specified authentication method).

sendImmediately supports Digest authentication when it is true.

OAuth login

// Twitter OAuth
var qs = require('querystring')
  , oauth =
    { callback: 'http://mysite.com/callback/'
    , consumer_key: CONSUMER_KEY
    , consumer_secret: CONSUMER_SECRET
    }
  , url = 'https://api.twitter.com/oauth/request_token'
  ;
request.post({url:url, oauth:oauth}, function (e, r, body) {
  // Ideally, you would take the body in the response
  // and construct a URL that a user clicks on (like a sign in button).
  // The verifier is only available in the response after a user has
  // verified with twitter that they are authorizing your app.
  var access_token = qs.parse(body)
    , oauth =
      { consumer_key: CONSUMER_KEY
      , consumer_secret: CONSUMER_SECRET
      , token: access_token.oauth_token
      , verifier: access_token.oauth_verifier
      }
    , url = 'https://api.twitter.com/oauth/access_token'
    ;
  request.post({url:url, oauth:oauth}, function (e, r, body) {
    var perm_token = qs.parse(body)
      , oauth =
        { consumer_key: CONSUMER_KEY
        , consumer_secret: CONSUMER_SECRET
        , token: perm_token.oauth_token
        , token_secret: perm_token.oauth_token_secret
        }
      , url = 'https://api.twitter.com/1/users/show.json?'
      , params =
        { screen_name: perm_token.screen_name
        , user_id: perm_token.user_id
        }
      ;
    url += qs.stringify(params)
    request.get({url:url, oauth:oauth, json:true}, function (e, r, user) {
      console.log(user)
    })
  })
})

Customize HTTP header

User-Agent and others can be set in options objects. In the following example, we call the github API to find out the number of collections and derivatives of a warehouse. We used custom User-Agent and https.

var request = require('request');

var options = {
    url: 'https://api.github.com/repos/mikeal/request',
    headers: {
        'User-Agent': 'request'
    }
};

function callback(error, response, body) {
    if (!error && response.statusCode == 200) {
        var info = JSON.parse(body);
        console.log(info.stargazers_count + " Stars");
        console.log(info.forks_count + " Forks");
    }
}

request(options, callback);

cookies

By default, cookies are disabled. Set jar to true in defaults or options so that cookies are used for subsequent requests.

var request = request.defaults({jar: true})
request('http://www.google.com', function () {
  request('http://images.google.com')
})

By creating a new instance of request.jar(), you can use a custom cookie instead of a request global cookie jar.

var j = request.jar()
var request = request.defaults({jar:j})
request('http://www.google.com', function () {
  request('http://images.google.com')
})

perhaps

var j = request.jar()
var cookie = request.cookie('your_cookie_here')
j.setCookie(cookie, uri, function (err, cookie){})
request({url: 'http://www.google.com', jar: j}, function () {
  request('http://images.google.com')
})

Note that setCookie requires at least three parameters, and the last one is the callback function.