Follow Redirects

Drop-in replacement for Node's `http` and `https` modules that automatically follows redirects.

`follow-redirects` provides request and get methods that behave identically to those found on the native http and https modules, with the exception that they will seamlessly follow redirects.

const { http, https } = require('follow-redirects');
http.get('http://bit.ly/900913', response => {
response.on('data', chunk => {
console.log(chunk);
});
}).on('error', 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.

const request = https.request({
host: 'bitly.com',
path: '/UHfDGO',
}, response => {
console.log(response.responseUrl);
// 'http://duckduckgo.com/robots.txt'
});
request.end();

# Options

## Global options

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

const 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:

const url = require('url');
const { http, https } = require('follow-redirects');
const options = url.parse('http://bit.ly/900913');
options.maxRedirects = 10;
options.beforeRedirect = (options, { headers }) => {
// Use this to adjust the request options upon redirecting,
// to inspect the latest response headers,
// or to cancel the request by throwing an error
if (options.hostname === "example.com") {
options.auth = "user:password";
}
};
http.request(options);

In addition to the standard HTTP and HTTPS options, 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.
- `beforeRedirect` (default: `undefined`) – optionally change the request `options` on redirects, or abort the request by throwing an error.
- `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() }`
- `trackRedirects` (default: `false`) – whether to store the redirected response details into the `redirects` array on the response object.

## Advanced usage

By default, `follow-redirects` will use the Node.js default implementations of `http` and `https`. To enable features such as caching and/or intermediate request tracking, you might instead want to wrap `follow-redirects` around custom protocol implementations:

const { http, https } = 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.

# Browser Usage

Due to the way the browser works, the `http` and `https` browser equivalents perform redirects by default.

By requiring `follow-redirects` this way:

const http = require('follow-redirects/http');
const https = require('follow-redirects/https');

you can easily tell webpack and friends to replace `follow-redirect` by the built-in versions:

{
"follow-redirects/http" : "http",
"follow-redirects/https" : "https"
}

# Contributing

Pull Requests are always welcome. Please file an issue 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 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

- Ruben Verborgh
- Olivier Lalonde
- James Talmage

# License

MIT License