## Follow Redirects

Drop-in replacement for Nodes `http` and `https` that automatically follows redirects.

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`follow-redirects` provides [request](https://nodejs.org/api/http.html#http_http_request_options_callback) and [get](https://nodejs.org/api/http.html#http_http_get_options_callback)
 methods that behave identically to those found on the native [http](https://nodejs.org/api/http.html#http_http_request_options_callback) and [https](https://nodejs.org/api/https.html#https_https_request_options_callback)
 modules, with the exception that they will seamlessly follow redirects.

```javascript
var http = require('follow-redirects').http;
var https = require('follow-redirects').https;

http.get('http://bit.ly/900913', function (response) {
  response.on('data', function (chunk) {
    console.log(chunk);
  });
}).on('error', function (err) {
  console.error(err);
});
```

You can inspect the final redirected URL through the `responseUrl` property on the `response`.
If no redirection happened, `responseUrl` is the original request URL.

```javascript
https.request({
  host: 'bitly.com',
  path: '/UHfDGO',
}, function (response) {
  console.log(response.responseUrl);
  // 'http://duckduckgo.com/robots.txt'
});
```

## Options
### Global options
Global options are set directly on the `follow-redirects` module:

```javascript
var followRedirects = require('follow-redirects');
followRedirects.maxRedirects = 10;
followRedirects.maxBodyLength = 20 * 1024 * 1024; // 20 MB
```

The following global options are supported:

- `maxRedirects` (default: `21`) – sets the maximum number of allowed redirects; if exceeded, an error will be emitted.

- `maxBodyLength` (default: 10MB) – sets the maximum size of the request body; if exceeded, an error will be emitted.


### Per-request options
Per-request options are set by passing an `options` object:

```javascript
var url = require('url');
var followRedirects = require('follow-redirects');

var options = url.parse('http://bit.ly/900913');
options.maxRedirects = 10;
http.request(options);
```

In addition to the [standard HTTP](https://nodejs.org/api/http.html#http_http_request_options_callback) and [HTTPS options](https://nodejs.org/api/https.html#https_https_request_options_callback),
the following per-request options are supported:
- `followRedirects` (default: `true`) – whether redirects should be followed.

- `maxRedirects` (default: `21`) – sets the maximum number of allowed redirects; if exceeded, an error will be emitted.

- `maxBodyLength` (default: 10MB) – sets the maximum size of the request body; if exceeded, an error will be emitted.

- `agents` (default: `undefined`) – sets the `agent` option per protocol, since HTTP and HTTPS use different agents. Example value: `{ http: new http.Agent(), https: new https.Agent() }`


### Advanced usage
By default, `follow-redirects` will use the Node.js default implementations
of [`http`](https://nodejs.org/api/http.html)
and [`https`](https://nodejs.org/api/https.html).
To enable features such as caching and/or intermediate request tracking,
you might instead want to wrap `follow-redirects` around custom protocol implementations:

```javascript
var followRedirects = require('follow-redirects').wrap({
  http: require('your-custom-http'),
  https: require('your-custom-https'),
});
```

Such custom protocols only need an implementation of the `request` method.

## Browserify Usage

Due to the way `XMLHttpRequest` works, the `browserify` versions of `http` and `https` already follow redirects.
 If you are *only* targeting the browser, then this library has little value for you. If you want to write cross
 platform code for node and the browser, `follow-redirects` provides a great solution for making the native node
 modules behave the same as they do in browserified builds in the browser. To avoid bundling unnecessary code
 you should tell browserify to swap out `follow-redirects` with the standard modules when bundling.
 To make this easier, you need to change how you require the modules:

```javascript
var http = require('follow-redirects/http');
var https = require('follow-redirects/https');
```

You can then replace `follow-redirects` in your browserify configuration like so:

```javascript
"browser": {
  "follow-redirects/http"  : "http",
  "follow-redirects/https" : "https"
}
```

The `browserify-http` module has not kept pace with node development, and no long behaves identically to the native
 module when running in the browser. If you are experiencing problems, you may want to check out
 [browserify-http-2](https://www.npmjs.com/package/http-browserify-2). It is more actively maintained and
 attempts to address a few of the shortcomings of `browserify-http`. In that case, your browserify config should
 look something like this:

```javascript
"browser": {
  "follow-redirects/http"  : "browserify-http-2/http",
  "follow-redirects/https" : "browserify-http-2/https"
}
```

## Contributing

Pull Requests are always welcome. Please [file an issue](https://github.com/olalonde/follow-redirects/issues)
 detailing your proposal before you invest your valuable time. Additional features and bug fixes should be accompanied
 by tests. You can run the test suite locally with a simple `npm test` command.

## Debug Logging

`follow-redirects` uses the excellent [debug](https://www.npmjs.com/package/debug) for logging. To turn on logging
 set the environment variable `DEBUG=follow-redirects` for debug output from just this module. When running the test
 suite it is sometimes advantageous to set `DEBUG=*` to see output from the express server as well.

## Authors

- Olivier Lalonde (olalonde@gmail.com)
- James Talmage (james@talmage.io)
- [Ruben Verborgh](https://ruben.verborgh.org/)

## License

MIT: [http://olalonde.mit-license.org](http://olalonde.mit-license.org)
