hyperapp-hmr

Persist the app state while the code reloads

A HyperApp mixin that lets you perform Hot Module Replacement without needing any ties into your build mechanism.

var { h, app } = require('hyperapp')
var hmr = require('hyperapp-hmr')

app({
  // Simply load HMR as a mixin
  mixins: [ hmr ],
  
  // The rest of your application stays unchanged, e.g. state:
  state: { count: 0 },

  // Try changing action's functionality as the app is running with HMR
  // Then when you reload, the state is persisted and the functions are updated
  actions: {
    add: (state) => ({ count: state.count + 1 })
  },

  // Also change the view freely with the HMR
  view: (state, actions) =>
    <div class='app'>
      <button onclick={actions.add}>Add one</button>
      <span>Current value: {state.count}</span>
    </div>
})

TODO: Replace this example with a screen capture of the test

See Usage for more details, and Testing for seeing an example

Install

npm i hyperapp-hmr

Usage

The module exports an hmr mixin, which will persist all of the app's state between reloads, so the actions and views can change seamlessly underneath.

Take an example: You go to a route on your page, open up a sidebar, click a button that opens a prompt, type in the prompt... These are a lot of steps you have to repeat over and over without the state being persisted. HMR solves this.

hmr

The mixin that you load into your app:

var hmr = require('hyperapp-hmr')

app({
  mixin: [ hmr ]
})

What about live-reloading?

Live-reloading is not provided out of the box in hyperapp-hmr because:

• There are standalone auto-reload servers you can opt-in to using with this package with no problems. For example, see budo for a prototyping tool that lets you live-reload super easy.
• There may be people who are uninterested in what it takes to setup auto-reloading, and don't mind just hitting F5 with the same HMR benefits.
• It would significantly increase the complexity of the package, as there would need to be a server-side so we could detect file changes, and communicate that to client-side for reloading, etc. which makes it less appealing to some.

Integration with Webpack?

I personally main Browserify, which is why there nothing made using module.hot.

That being said, happy to accept PRs that can integrate those features with the same usage shown here.

Testing

To run the tests, clone the repository and run:

npm i
npm run test:browser

This will create temporary server that hosts and live-reloads test/index.js.

Go into test/index.js and make edits to the view and actions see if the HMR is working.

(Note: it is intentionally not npm test so release tools don't think they're unit tests)