Trailers

HTTP is amazing, it has amazing features that most of us aren't using. One of these features are trailing headers. These are headers that can be send after you've already written your initial HTTP headers. The only caveat is that they only work with transfer-encoding: chunked, luckly, this is enabled by default in Nodejs.

Installation

The module can be downloaded from the npm registry:

npm install --save trailers

The --save tells npm to automatically add the installed version to your package.json

Usage

When using this module, nothing changes how you and program your Node.js applications. The only difference is that you can write headers AFTER you've written the headers of your response. You can still use res.setHeaders just like you would normally do.

To run this module simply include it in your application:

require('trailers');

That's it. Everything is magically fixed.

The magic

The module overrides the prototypes of the OutgoingMessage class in Node.js which is what you get a Response object in a HTTP server. The setHeader method is overridden method to check if the headers are already flushed to the client and queues the headers in a new trailers object when they are already written. We override the end method so we can flush these headers using the addTrailers method.

License

MIT