Node Cookbook - Third Edition

Creating a plugin

Let's copy the app folder from our main recipe to the custom-plugin-app and create a plugins folder with an answer.js file:

$ cp -fr app custom-plugin-app
$ cd custom-plugin-app
$ mkdir plugins
$ touch plugins/answer.js

We'll make the contents of plugins/answer.js look like so:

module.exports = answer 
 
function answer (server, options, next) { 
  server.ext('onPreResponse', (request, reply) => { 
    request.response.header('X-Answer', 42) 
    reply.continue() 
  }) 
  next() 
} 
 
answer.attributes = {name: 'answer'} 

The next callback is supplied to allow for any asynchronous activity. We call it to let Hapi know we've finished setting up the plugin. Under the hood Hapi would call the server.register callback once all the plugins had called ...