app-bridge

Create a bridge.

Intended to be used as a global singleton request/response broker between independently loaded scripts that share the same Javascript contexts.

Install

$ npm install --save app-bridge

Usage

In your "master" shell app:

const Bridge = require('app-bridge/singleton')
const loadScriptOnce = require('load-script-once')

const bridge = Bridge({
  methods: {
    loadChildApp: {
      request: {
        middleware: [(next) => loadScriptOnce('/child-app.js', next)]
      },
      response: {
        validate: (data) => assert.ok(data && data.innerHTML, 'expected an element')
      }
    }
  }
})

function mountChildApp (params) {
  bridge.methods.loadChildApp(params, function (error, element) {
    parentElement.appendChild(element)
  })
}

In your child app (child-app.js, loaded async):

const bridge = require('app-bridge/singleton')()

bridge.listen(bridge.methods.loadChildApp, function (data, respond) {
  const element = document.createElement('child-app')
  element.innerHTML = JSON.stringify(data)

  respond(null, element)
})

API

require('app-bridge')

Bridge(options) -> bridge

options

An object with a property methods, which is also an object, with the following properties:

• request: Object
  • validate: Function(data) => Error? - if validate returns or throws an error, the request fails.
  • middleware: Array<Function(callback)> - an array of asynchronous functions to run in order before sending the request.
• response: Object
  • validate: Function(data) => Error? - if validate function returns or throws an error, the response fails.
  • middleware: Array<Function(callback)> - an array of asynchronous functions to run in order before sending the response.

bridge.methods.{methodName}(payload, callback)

Methods will be defined under the object bridge.methods matching the name of every key you passed into options.methods.

payload: any

Data to pass to this method's listener.

callback

A function which takes parameters (error, data).

It is called with an error if an error occurs in any validate or middleware function, or if the listener responds with an error.

Otherwise, it is called with data that the listener responded with.

bridge.listen(method, callback)

method

A reference to one of the methods under bridge.methods.

listener

A function that will be called with (data, respond) when a message is sent on this channel.

Respond should be called with (error, responseData).

require('app-bridge/singleton')

This is the same as requiring the main file, except it creates or returns a singleton stored on the window.

The intention is that your "master" app will create the bridge using app-bridge/singleton, and your child apps will get that global bridge once they are asynchronously loaded.

License

MIT © Andrew Joslin