plug-and-play

Node.js Plugable package

Easily create hooks and let users plug their own logic across your code to make it extensible by everyone with new features.

Main features

• Extention points definition
  Simple to declare new extention points, yet a lot of flexibility to the plugin authors.
• Hook definition
  Plugin writer can intercept calls to a function by placing their own logicl before, after and even switching the default implementation.
• Dependency management
  Plugins can require other plugins as required dependencies as well as choose the order of execution of each hook.
• Promise support
  Hook can be synchronous and asynchronous when returning a promise.
• Nested/hierachical
  Instanciate plugin instances with a parent reference and parent hooks will also be available inside the children.

Learning

We encourage your to read the detailed tutorial on how to create a plugin architected with Plug and Play published by Adaltas.

Quick example

Library and application authors must define hooks, see ./sample/lib.js:

const plugandplay = require('plug-and-play')

const plugins = plugandplay()

module.exports = {
  // Create and export a new Plug and Play instance
  plugins: plugins,
  // Our core library function
  print: function() {
    // Wrap-up code
    plugins.call({
      // Identify this hook with a name
      name: 'hooks:print',
      // Expose arguments to plugins authors
      args: {
        data: { message: 'hello' }
      },
      // Default implementation
      handler: ({data}) => {
        // Original library
        console.log(data.message)
      }
    })
  }
}

Users and pluging authors can now register their own hooks, see ./sample/index.js:

const mysuperlibrary = require('./lib')

mysuperlibrary.plugins.register({
  hooks: {
    'hooks:print': ({data}, handler) => {
      // Alter the argument
      data.message = 'Hello World'
      // Print a message before the library code
      console.log('>>>>>>>>>>>')
      // Call the original handler
      const result = handler.call(null, {data: data})
      // Print a message after the library code
      console.log('<<<<<<<<<<<')
      return result
    }
  }
})
mysuperlibrary.print()

While the original print function was only printing Hello to stdout, the introduction of this new plugin prints:

>>>>>>>>>>>
Hello world
<<<<<<<<<<<