urllib

What is urllib?

The urllib npm package is a utility library for making HTTP requests and handling URLs. It provides a simple and flexible API for performing various types of HTTP requests, handling query parameters, and working with URLs.

What are urllib's main functionalities?

HTTP GET Request

This feature allows you to make a simple HTTP GET request to a specified URL. The callback function handles the response data or any errors that occur.

const urllib = require('urllib');

urllib.request('https://api.example.com/data', function (err, data, res) {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data.toString());
});

HTTP POST Request

This feature allows you to make an HTTP POST request with a payload. The data object contains the key-value pairs to be sent in the request body.

const urllib = require('urllib');

urllib.request('https://api.example.com/data', {
  method: 'POST',
  data: {
    key1: 'value1',
    key2: 'value2'
  }
}, function (err, data, res) {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data.toString());
});

Handling Query Parameters

This feature allows you to include query parameters in your HTTP request. The data object is automatically serialized into a query string and appended to the URL.

const urllib = require('urllib');

const params = {
  key1: 'value1',
  key2: 'value2'
};

urllib.request('https://api.example.com/data', {
  data: params
}, function (err, data, res) {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data.toString());
});

Custom Headers

This feature allows you to set custom headers for your HTTP request. The headers object contains key-value pairs representing the header names and values.

const urllib = require('urllib');

urllib.request('https://api.example.com/data', {
  headers: {
    'Authorization': 'Bearer token',
    'Content-Type': 'application/json'
  }
}, function (err, data, res) {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data.toString());
});

Other packages similar to urllib

axios

Axios is a promise-based HTTP client for the browser and Node.js. It provides a more modern and flexible API compared to urllib, with support for interceptors, request cancellation, and automatic JSON data transformation.

node-fetch

Node-fetch is a lightweight module that brings the Fetch API to Node.js. It is a minimalistic alternative to urllib, focusing on simplicity and compliance with the Fetch standard.

request

Request is a simplified HTTP client for Node.js with a rich set of features. It is more feature-rich than urllib, offering support for OAuth, cookies, and multipart form data. However, it has been deprecated in favor of more modern alternatives like axios.

README

urllib@2

Request HTTP URLs in a complex world — basic and digest authentication, redirections, cookies, timeout and more.

Install

$ npm install urllib@2 --save

Usage

callback

var urllib = require('urllib');

urllib.request('http://cnodejs.org/', function (err, data, res) {
  if (err) {
    throw err; // you need to handle error
  }
  console.log(res.statusCode);
  console.log(res.headers);
  // data is Buffer instance
  console.log(data.toString());
});

Promise

If you've installed bluebird, bluebird will be used. urllib does not install bluebird for you.

Otherwise, if you're using a node that has native v8 Promises (v0.11.13+), then that will be used.

Otherwise, this library will crash the process and exit, so you might as well install bluebird as a dependency!

var urllib = require('urllib');

urllib.request('http://nodejs.org').then(function (result) {
  // result: {data: buffer, res: response object}
  console.log('status: %s, body size: %d, headers: %j', result.res.statusCode, result.data.length, result.res.headers);
}).catch(function (err) {
  console.error(err);
});

co & generator

If you are using co or koa:

var co = require('co');
var urllib = require('urllib');

co(function* () {
  var result = yield urllib.requestThunk('http://nodejs.org');
  console.log('status: %s, body size: %d, headers: %j',
    result.status, result.data.length, result.headers);
})();

Global response event

You should create a urllib instance first.

var httpclient = require('urllib').create();

httpclient.on('response', function (info) {
  error: err,
  ctx: args.ctx,
  req: {
    url: url,
    options: options,
    size: requestSize,
  },
  res: res
});

httpclient.request('http://nodejs.org', function (err, body) {
  console.log('body size: %d', body.length);
});

API Doc

Method: http.request(url[, options][, callback])

Arguments

• url String | Object - The URL to request, either a String or a Object that return by url.parse.
• options Object - Optional
  • method String - Request method, defaults to GET. Could be GET, POST, DELETE or PUT. Alias 'type'.
  • data Object - Data to be sent. Will be stringify automatically.
  • dataAsQueryString Boolean - Force convert data to query string.
  • content String | Buffer - Manually set the content of payload. If set, data will be ignored.
  • stream stream.Readable - Stream to be pipe to the remote. If set, data and content will be ignored.
  • writeStream stream.Writable - A writable stream to be piped by the response stream. Responding data will be write to this stream and callback will be called with data set null after finished writing.
  • files {Array<ReadStream|Buffer|String> | Object | ReadStream | Buffer | String - The files will send with multipart/form-data format, base on formstream. If method not set, will use POST method by default.
  • consumeWriteStream [true] - consume the writeStream, invoke the callback after writeStream close.
  • contentType String - Type of request data. Could be json (Notes: not use application/json here). If it's json, will auto set Content-Type: application/json header.
  • nestedQuerystring Boolean - urllib default use querystring to stringify form data which don't support nested object, will use qs instead of querystring to support nested object by set this option to true.
  • dataType String - Type of response data. Could be text or json. If it's text, the callbacked data would be a String. If it's json, the data of callback would be a parsed JSON Object and will auto set Accept: application/json header. Default callbacked data would be a Buffer.
  • fixJSONCtlChars Boolean - Fix the control characters (U+0000 through U+001F) before JSON parse response. Default is false.
  • headers Object - Request headers.
  • keepHeaderCase Boolean - by default will convert header keys to lowercase
  • timeout Number | Array - Request timeout in milliseconds for connecting phase and response receiving phase. Defaults to exports.TIMEOUT, both are 5s. You can use timeout: 5000 to tell urllib use same timeout on two phase or set them seperately such as timeout: [3000, 5000], which will set connecting timeout to 3s and response 5s.
  • auth String - username:password used in HTTP Basic Authorization.
  • digestAuth String - username:password used in HTTP Digest Authorization.
  • agent http.Agent - HTTP Agent object. Set false if you does not use agent.
  • httpsAgent https.Agent - HTTPS Agent object. Set false if you does not use agent.
  • ca String | Buffer | Array - An array of strings or Buffers of trusted certificates. If this is omitted several well known "root" CAs will be used, like VeriSign. These are used to authorize connections. Notes: This is necessary only if the server uses the self-signed certificate
  • rejectUnauthorized Boolean - If true, the server certificate is verified against the list of supplied CAs. An 'error' event is emitted if verification fails. Default: true.
  • pfx String | Buffer - A string or Buffer containing the private key, certificate and CA certs of the server in PFX or PKCS12 format.
  • key String | Buffer - A string or Buffer containing the private key of the client in PEM format. Notes: This is necessary only if using the client certificate authentication
  • cert String | Buffer - A string or Buffer containing the certificate key of the client in PEM format. Notes: This is necessary only if using the client certificate authentication
  • passphrase String - A string of passphrase for the private key or pfx.
  • ciphers String - A string describing the ciphers to use or exclude.
  • secureProtocol String - The SSL method to use, e.g. SSLv3_method to force SSL version 3.
  • followRedirect Boolean - follow HTTP 3xx responses as redirects. defaults to false.
  • maxRedirects Number - The maximum number of redirects to follow, defaults to 10.
  • formatRedirectUrl Function - Format the redirect url by your self. Default is url.resolve(from, to).
  • beforeRequest Function - Before request hook, you can change every thing here.
  • streaming Boolean - let you get the res object when request connected, default false. alias customResponse
  • gzip Boolean - Accept gzip response content and auto decode it, default is false.
  • timing Boolean - Enable timing or not, default is false.
  • enableProxy Boolean - Enable proxy request, default is false.
  • proxy String | Object - proxy agent uri or options, default is null.
  • lookup Function - Custom DNS lookup function, default is dns.lookup. Require node >= 4.0.0(for http protocol) and node >=8(for https protocol)
  • checkAddress Function: optional, check request address to protect from SSRF and similar attacks. It receive tow arguments(ip and family) and should return true or false to identified the address is legal or not. It rely on lookup and have the same version requirement.
  • trace Boolean - Enable capture stack include call site of library entrance, default is false.
  • socketPath String - optional Unix Domain Socket. (Refer to Node.js Document)
• callback(err, data, res) Function - Optional callback.
  • err Error - Would be null if no error accured.
  • data Buffer | Object - The data responsed. Would be a Buffer if dataType is set to text or an JSON parsed into Object if it's set to json.
  • res http.IncomingMessage - The response.

Returns

http.ClientRequest - The request.

Calling .abort() method of the request stream can cancel the request.

Options: options.data

When making a request:

urllib.request('http://example.com', {
  method: 'GET',
  data: {
    'a': 'hello',
    'b': 'world'
  }
});

For GET request, data will be stringify to query string, e.g. http://example.com/?a=hello&b=world.

For others like POST, PATCH or PUT request, in defaults, the data will be stringify into application/x-www-form-urlencoded format if Content-Type header is not set.

If Content-type is application/json, the data will be JSON.stringify to JSON data format.

Options: options.content

options.content is useful when you wish to construct the request body by yourself, for example making a Content-Type: application/json request.

Notes that if you want to send a JSON body, you should stringify it yourself:

urllib.request('http://example.com', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  content: JSON.stringify({
    a: 'hello',
    b: 'world'
  })
});

It would make a HTTP request like:

POST / HTTP/1.1
Host: example.com
Content-Type: application/json

{
  "a": "hello",
  "b": "world"
}

This exmaple can use options.data with application/json content type:

urllib.request('http://example.com', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  data: {
    a: 'hello',
    b: 'world'
  }
});

Options: options.files

Upload a file with a hello field.

var urllib = request('urllib');

var req = urllib.request('http://my.server.com/upload', {
  files: __filename,
  data: {
    hello: 'hello urllib',
  },
}, function (err, data, res) {
  // upload finished
});

Upload multi files with a hello field.

var urllib = request('urllib');

var req = urllib.request('http://my.server.com/upload', {
  files: [
    __filename,
    fs.createReadStream(__filename),
    Buffer.from('mock file content'),
  ],
  data: {
    hello: 'hello urllib with multi files',
  },
}, function (err, data, res) {
  // upload finished
});

Custom file field name with uploadfile.

var urllib = request('urllib');

var req = urllib.request('http://my.server.com/upload', {
  files: {
    uploadfile: __filename,
  },
}, function (err, data, res) {
  // upload finished
});

Options: options.stream

Uploads a file with formstream:

var urllib = require('urllib');
var formstream = require('formstream');

var form = formstream();
form.file('file', __filename);
form.field('hello', '你好urllib');

var req = urllib.request('http://my.server.com/upload', {
  method: 'POST',
  headers: form.headers(),
  stream: form
}, function (err, data, res) {
  // upload finished
});

Response Object

Response is normal object, it contains:

• status or statusCode: response status code.
  • -1 meaning some network error like ENOTFOUND
  • -2 meaning ConnectionTimeoutError
• statusMessage: response status message.
• headers: response http headers, default is {}
• size: response size
• aborted: response was aborted or not
• rt: total request and response time in ms.
• timing: timing object if timing enable.
• remoteAddress: http server ip address
• remotePort: http server ip port
• socketHandledRequests: socket already handled request count
• socketHandledResponses: socket already handled response count

Response: res.aborted

If the underlaying connection was terminated before response.end() was called, res.aborted should be true.

require('http').createServer(function (req, res) {
  req.resume();
  req.on('end', function () {
    res.write('foo haha\n');
    setTimeout(function () {
      res.write('foo haha 2');
      setTimeout(function () {
        res.socket.end();
      }, 300);
    }, 200);
    return;
  });
}).listen(1984);

urllib.request('http://127.0.0.1:1984/socket.end', function (err, data, res) {
  data.toString().should.equal('foo haha\nfoo haha 2');
  should.ok(res.aborted);
  done();
});

HttpClient2

HttpClient2 is a new instance for future. request method only return a promise, compatible with async/await and generator in co.

Options

options extends from urllib, besides below

• retry Number - a retry count, when get an error, it will request again until reach the retry count.
• retryDelay Number - wait a delay(ms) between retries.
• isRetry Function - determine whether retry, a response object as the first argument. it will retry when status >= 500 by default. Request error is not included.

Warning

It's not supported by using retry and writeStream, because the retry request can't stop the stream which is consuming.

Proxy

Support both http and https protocol.

Notice: Only support on Node.js >= 4.0.0

Programming

urllib.request('https://twitter.com/', {
  enableProxy: true,
  proxy: 'http://localhost:8008',
}, (err, data, res) => {
  console.log(res.status, res.headers);
});

System environment variable

• http

HTTP_PROXY=http://localhost:8008
http_proxy=http://localhost:8008

• https

HTTP_PROXY=http://localhost:8008
http_proxy=http://localhost:8008
HTTPS_PROXY=https://localhost:8008
https_proxy=https://localhost:8008

$ http_proxy=http://localhost:8008 node index.js

Trace

If set trace true, error stack will contains full call stack, like

Error: connect ECONNREFUSED 127.0.0.1:11
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1113:14)
    --------------------
    at ~/workspace/urllib/lib/urllib.js:150:13
    at new Promise (<anonymous>)
    at Object.request (~/workspace/urllib/lib/urllib.js:149:10)
    at Context.<anonymous> (~/workspace/urllib/test/urllib_promise.test.js:49:19)
    ....

When open the trace, urllib may have poor perfomance, please consider carefully.

TODO

• Support component
• Browser env use Ajax
• [√] Support Proxy
• [√] Upload file like form upload
• [√] Auto redirect handle
• [√] https & self-signed certificate
• [√] Connection timeout & Response timeout
• [√] Support Accept-Encoding=gzip by options.gzip = true
• [√] Support Digest access authentication

Contributors

fengmk2	dead-horse	xingrz	popomore	JacksonTian	ibigbug
greenkeeperio-bot	atian25	paambaati	denghongcai	XadillaX	alsotang
leoner	hyj1991	isayme	killagu	cyjake	whxaxes
chadxz	danielwpz	danielsss	Jeff-Tian	jedahan	nick-ng
rishavsharan	willizm	davidkhala	aleafs	Amunu	azure-pipelines[bot]
changzhiwin	yuzhigang33	fishbar	gxcsoccer	mars-coder	rockdai
dickeylth	aladdin-add

This project follows the git-contributor spec, auto updated at Tue Jul 05 2022 16:17:31 GMT+0800.

License

MIT