Integrating Hyperapp Into Legacy MVCs

So you have discovered the wonderful world of Hyperapp and you want to use it at work or on an older project to revamp the frontend a little bit. What are the first steps?


If your app is built with something like Rails/Django/Phoenix/Laravel it would make sense to keep the routing on backend since it does that job really well.

But how will I make an SPA?

You won’t make one but many! The idea will be that you app already has places your users go to, patterns they are used to, and workflows that are in place. So each route will be it’s own SPA, or have a few hyperapps.

Example structure (using Rails as an example):

even though I am going to use Rails as an example, the same concepts apply for using EJS with Node/Express, etc..

# Header/Navbar partial

<div id="navbar_root">
  <%= javascript_pack_tag 'navbar' %> # Profile page partial

  <div id="profile_page_root">
    <%= javascript_pack_tag 'profilePage' %> # Footer partial

    <div id="footer_root">
      <%= javascript_pack_tag 'footer' %>

Each partial (traditional server side template component) will have its own Hyperapp that calls in a seperate bundle. Each bundle can use shared components (views) but the bundles themselves will be unique, as each partial is unique.

javascript_pack_tag here simply refers a chunkHash that webpacker (the Rails solution to using webpack) makes when writing a bundle.

Structure looks like so:

javascript / appActions / appState / models / appComponents / SomeView.js;
utils / sharedInternalUtils.js;
packs / profilePage.js;

Components can be shared while having individual packs!

Now, we need to talk about the bootstrapping process. This will be important.

When your JS hits the page your backend is the source of truth, and since some of the HTML is still being rendered server side, you can take advantage of the backend and have it feed your frontend information like:


Now you can create HTML safe JSON for your frontend to grab:

<script id="profile_page_data">
  <%= {
    current_user: @current_user,
    endpoint: @endpoint,
    can_edit_page: @can_edit_page,
    can_upload_picture_larger_than_2mb: @can_upload_picture_larger_than_2mb,
  }.to_json.html_safe %>

This way you can create even more dynamic view functions for your app! Now that you never have to hardcode an API endpoint again, your views will continue to work without exploding because some API call has changed when the backend team has refactored routes or something of that nature.

You pull in some data from the DOM, then make an API call for custom user data.

Now you need to grab the data (in your pack tag prior to calling your comp/view)

// profilePage.js

import { app } from "hyperapp";
import { state, actions } from "./../models/ProfilePageModel";
import ProfilePageComp from "./../components/ProfilePageComp";

const { innerHTML } = document.getElementById("profile_page_data");
const data = JSON.parse(dataNode.innerHTML);

// now that you have some backend data, merge it with your app state
const appState = Object.assign({}, state, data);

const { someAction, anotherAction, makeApiCall } = app(

// make the intial api call to populate the DOM with user specific profile data


Now let’s say that the profilePage entry point is in the middle of some DOM that is bound by jQuery. That jQuery can still talk to the Hyperapp app via exposed actions!

const {
} = app(

  Say for some reason that your ProfilePageComp maintains all internal state
  but because designers are hard at work redesigning the section just below all
  the cogs and wigdgets built in Hyperapp, that the save button is still part of
  the jQuery part of the page, now you can just change the function it calls!
$('#saveProfile').on('click', someActionThatSavesTheProfile);

Hyperapps can talk to eachother this way too. Here is an example I wrote on Codepen of plain old JS talking to HA. Which means that if someone adds an item to their cart, the ItemsApp can still make a call to an exposed NavBar actions that will update the cart number for example.

Hyperapps can talk to jQuery the old fashioned way, but I would try my best to never mix jQuery inside the VDOM!


The big advantage here is that because we can sprinkle in little apps one by one, eventually all of the components can get merged once a certain route is finished being completely converted, and then you can start utilizing a frontend router and just keep the backend as an Auth mecahnism and an API.