Vue inside Phoenix LiveView with seamless end-to-end reactivity.

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• Phoenix LiveView

• Features
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• Example
• Installation
• Usage
• Deployment
• FAQ

• ⚡ End-To-End Reactivity with LiveView
• 🔋 Server-Side Rendered (SSR) Vue
• 🐌 Lazy-loading Vue Components
• 🪄 Sigil as an Alternative LiveView DSL
• 🦄 Tailwind Support
• 💀 Dead View Support
• 🦥 Slot Interoperability
• 🚀 Amazing DX with Vite

After installation, you can use Vue components in the same way as you'd use functional LiveView components. You can even handle Vue events with JS hooks! All the phx-click, phx-change attributes works inside Vue components as well.

<script setup lang="ts">
import {ref} from "vue"
const props = defineProps<{count: number}>()
const emit = defineEmits<{inc: [{value: number}]}>()
const diff = ref<string>("1")
</script>

<template>
    Current count
    <div class="text-2xl text-bold">{{ props.count }}</div>
    <label class="block mt-8">Diff: </label>
    <input v-model="diff" class="my-4" type="range" min="1" max="10" />

    <button
        @click="emit('inc', {value: parseInt(diff)})"
        class="bg-black text-white rounded p-2"
    >
        Increase counter by {{ diff }}
    </button>
</template>

defmodule LiveVueExamplesWeb.LiveCounter do
  use LiveVueExamplesWeb, :live_view

  def render(assigns) do
    ~H"""
    <.vue
      count={@count}
      v-component="Counter"
      v-socket={@socket}
      v-on:inc={JS.push("inc")}
    />
    """
  end

  def mount(_params, _session, socket) do
    {:ok, assign(socket, :count, 0)}
  end

  def handle_event("inc", %{"value" => diff}, socket) do
    {:noreply, update(socket, :count, &(&1   diff))}
  end
end

This project is heavily inspired by ✨ LiveSvelte ✨. Both projects try to solve the same problem. LiveVue was started as a fork fo LiveSvelte with adjusted ESbuild settings, and evolved to use Vite and a slightly different syntax. I strongly believe more options are always better, and since I love Vue and it's ecosystem I've decided to give it a go 😉

You can read more about differences between Vue and Svelte in FAQ.

Phoenix Live View makes it possible to create rich, interactive web apps without writing JS.

But once you'll need to do anything even slightly complex on the client-side, you'll end up writing lots of imperative, hard-to-maintain hooks.

LiveVue allows to create hybrid apps, where part of the session state is on the server and part on the client.

• Your hooks are starting to look like jQuery
• You have a complex local state
• You'd like to use a massive Vue ecosystem
• You want transitions, graphs etc.
• You simply like Vue 😉

See Installation.

By default, vue components should be placed either inside assets/vue directory or colocated with your Elixir files. You can configure that behaviour by changing assets/vue/index.js and use LiveVue.Components, vue_root: ["your/vue/dir"].

To render vue component from HEEX, you have to use <.vue> function with these attributes:

Instead of writing <.vue v-component="Counter"> you can use shortcut <.Counter>. Function names are generated based on filenames of found .vue files, so assets/vue/helpers/nested/Modal.vue will generate helper <.Modal>. If there are multiple .vue files with equal names, use <.vue v-component="path/to/file">

You pass props in the same way as with functional components in Elixir. All 3 examples does exactly the same.

<.vue
  count={@count}
  name={@name}
  v-component="Counter"
  v-socket={@socket}
/>

<.vue
  v-component="Counter"
  v-socket={@socket}
  {%{count: @count, name: @name}}
/>

<.Counter
  count={@count}
  name={@name}
  v-socket={@socket}
/>

All regular phoenix hooks like phx-click, phx-submit work as expected. To keep components DRY you can define vue handlers using v-on:eventname={JS.handler()} syntax. All attributes starting with v-on: are attached as emit handlers to Vue components and executed in the same way as Phoenix does it.

JS.push("someName") is a special case - if JS.push defines no value, it will be replaced by the emit payload.

<.vue v-on:submit={JS.push("submit")} v-component="SomeForm" v-socket={@socket} />
<.vue
  v-on:shoot={JS.push("shoot")}
  v-on:close={JS.hide()}
  v-component="SomeGame"
  v-socket={@socket}
/>

You can even pass slots to the vue component! They're passed to vue as raw HTML, so hooks in the slots won't work. Each slot is wrapped in a div due to technical limitations.

• Default slot can be passed as :inner_block and rendered inside Vue components as <slot />.
• Named slots can be passed by using <:slot_name>Content</:slot_name> syntax are rendered using <slot name="slot_name" /> syntax.
• Slots will be kept in sync, as expected.

An example:

<.Card title="The coldest sunset" v-socket={@socket}>
  <p>This is card content passed from phoenix!</p>
  <p>Even icons are working! <.icon name="hero-information-circle-mini" /></p>
  <:footer>And this is a footer from phoenix</:footer>
</.Card>

<template>
    <slot></slot>
    Footer:
    <slot name="footer"></slot>
</template>

You can use <.vue> components in dead views. Of course, there will be no updates on assign changes, since there is no websocket connection established to support it.

v-socket={@socket} is not required in dead views.

Vue SSR is compiled down into string concatenation, so it's quite fast 😉

In development it's recommended to use config :live_vue, ssr_module: LiveVue.SSR.ViteJS. It does HTTP call to vite /ssr_render endpoint added by LiveVue plugin, which in turn uses vite ssrLoadModule for efficient compilation.

In production it's recommended to use config :live_vue, ssr_module: LiveVue.SSR.NodeJS which uses NodeJS package directly talking with a JS process with a in-memory server bundle. By default, SSR bundle is saved to priv/vue/server.js.

You can use function useLiveVue to access root phoenix element where Vue component was routed.

API of that object is described in Phoenix docs.

Example

<script>
import {useLiveVue} from "live_vue"

const hook = useLiveVue()

hook.pushEvent("hello", {value: "from Vue"})
</script>

We can go one step further and use LiveVue as an alternative to the standard LiveView DSL. This idea is taken from LiveSvelte.

Take a look at the following example:

defmodule ExampleWeb.LiveSigil do
  use ExampleWeb, :live_view

  def render(assigns) do
    ~V"""
    <script setup lang="ts">
    import {ref} from "vue"
    const props = defineProps<{count: number}>()
    const diff = ref<number>(1)
    </script>

    <template>
      Current count
      <div class="text-2xl text-bold">{{ props.count }}</div>
      <label class="block mt-8">Diff: </label>
      <input v-model="diff" class="mt-4" type="range" min="1" max="10">

      <button
        phx-click="inc"
        :phx-value-diff="diff"
        class="mt-4 bg-black text-white rounded p-2 block">
        Increase counter {{ diff }}
      </button>
    """
  end

  def mount(_params, _session, socket) do
    {:ok, assign(socket, count: 0)}
  end

  def handle_event("inc", %{"diff" => diff}, socket) do
    {:noreply, update(socket, :count, &(&1   String.to_integer(diff)))}
  end
end

Use the ~V sigil instead of ~H and your LiveView will be Vue instead of an HEEx template.

Lazy loading Vue components is fully supported. You just need to return function returning promise in components passed to getHooks(components).

It can be done by using eager: false in import.meta.glob('./yourdir/*.vue', { eager: false, import: 'default' }) or by explicitly constructing components object. If SSR is enabled, all related JS and CSS files will be preloaded in HTML.

import component1 from "./Component1.vue"
import component2 from "./Component2.vue"
const entryComponents = {
    Component1: component1,
    Component2: component2,
    Component3Lazy: () => import("./Component3.vue"),
}

// in app.js
const hooks = getHooks(entryComponents)

If you want to initialize Vue app in a custom way, by eg. adding plugins or directives, you should pass initialization function to useHooks as in the following snippet

// in app.js
// ...
import {getHooks, initializeVueApp} from "live_vue"
// import { createPinia } from "pinia"
// const pinia = createPinia()

const initializeApp = context => {
    // initializeVueApp is a default function creating and initializing LiveVue App
    const app = initializeVueApp(context)
    // you can initialize additional plugins here, eg. Pinia
    // app.use(pinia)
    return app
}

const hooks = getHooks(components, {initializeApp})

You can completely change the default initialization method by not using initializeVueApp and rolling your own. Current implementation looks like this, feel free to adjust to your needs.

import {h} from "vue"

const initializeVueApp = ({createApp, component, props, slots, plugin, el}) => {
    const renderFn = () => h(component, props, slots)
    const app = createApp({render: renderFn})
    app.use(plugin)
    app.mount(el)
    return app
}

Context object passed to initializeApp has following keys:

You can use /example_project as a way to test live_vue locally.

You can also use your own project.

Clone live_vue to the parent directory of the project you want to test it in.

Inside mix.exs

{:live_vue, path: "../live_vue"},

Inside assets/package.json

"live_vue": "file:../../live_vue",

Make the changes in /assets/js and run:

mix assets.build

Or run the watcher:

mix assets.build --watch

Release is done with expublish package.

• Write version changelog in untracked RELEASE.md file
• Update version in README.md

Run

git add README.md
git commit -m "README version bump"

# to ensure everything works fine
mix expublish.minor --dry-run --allow-untracked --branch=main

# to publish everything
mix expublish.minor --allow-untracked --branch=main

Deploying a LiveVue app is the same as deploying a regular Phoenix app, except that you will need to ensure that nodejs (version 19 or later) is installed in your production environment.

The below guide shows how to deploy a LiveVue app to Fly.io, but similar steps can be taken to deploy to other hosting providers. You can find more information on how to deploy a Phoenix app here.

The following steps are needed to deploy to Fly.io. This guide assumes that you'll be using Fly Postgres as your database. Further guidance on how to deploy to Fly.io can be found here.

1. Generate a Dockerfile:

mix phx.gen.release --docker

2. Modify the generated Dockerfile to install curl, which is used to install nodejs (version 19 or greater), and also add a step to install our npm dependencies:

# ./Dockerfile

...

# install build dependencies
- RUN apt-get update -y && apt-get install -y build-essential git \
  RUN apt-get update -y && apt-get install -y build-essential git curl \
    && apt-get clean && rm -f /var/lib/apt/lists/*_*

  # install nodejs for build stage
  RUN curl -fsSL https://deb.nodesource.com/setup_19.x | bash - && apt-get install -y nodejs

...

COPY assets assets

  # install all npm packages in assets directory
  RUN cd /app/assets && npm install

...

# start a new build stage so that the final image will only contain
# the compiled release and other runtime necessities
FROM ${RUNNER_IMAGE}

RUN apt-get update -y && \
-  apt-get install -y libstdc  6 openssl libncurses5 locales ca-certificates \
   apt-get install -y libstdc  6 openssl libncurses5 locales ca-certificates curl \
   && apt-get clean && rm -f /var/lib/apt/lists/*_*

  # install nodejs for production environment
  RUN curl -fsSL https://deb.nodesource.com/setup_19.x | bash - && apt-get install -y nodejs

...

Note: nodejs is installed BOTH in the build stage and in the final image. This is because we need nodejs to install our npm dependencies and also need it when running our app.

3. Launch your app with the Fly.io CLI:

fly launch

4. When prompted to tweak settings, choose y:

? Do you want to tweak these settings before proceeding? (y/N) y

This will launch a new window where you can tweak your launch settings. In the database section, choose Fly Postgres and enter a name for your database. You may also want to change your database to the development configuration to avoid extra costs. You can leave the rest of the settings as-is unless you want to change them.

Deployment will continue once you hit confirm.

5. Once the deployment completes, run the following command to see your deployed app!

fly apps open

Yes, I noticed it slightly too late to change. Some helpful reddit users pointed it out 😉

I'd suggest refering to it as LiveVuejs in speech, to avoid confusion.

Both LiveVue and LiveSvelte serves the same purpose and are implemented in a very similar way. Here is a list of points to consider when choosing one over another:

• Vue uses virtual DOM, Svelte doesn't. Vue bundle is slightly bigger than Svelte because of runtime.
• Vue performance is very similar, or even better, than Svelte. Both are fast enough that you shouldn't make your decision based on it.
• Vue is working on a Vapor mode without virtual DOM. Once stable I'll try to support it here.
• Svelte reactivity is done based on the compilation step figuring out dependencies. It allows for a very concise syntax, but causes problems when you'd like to keep reactivity cross-files and has some limitations. Svelte 5 Runes will be very similar to Vue ref.
• Vue reactivity is based on JS Proxies. Syntax is a bit more verbose, but there are less ways to shoot yourself in a foot 😉
• Vue is more popular than Svelte, and has a bigger ecosystem. It might be an important thing to consider when making a decision.

Vue files in LiveVue have similar role as HEEX templates. In many cases it makes sense to colocate them next to your LiveViews for better DX.

You don't need to do anything to make it work, simply place your Vue files inside lib/my_app_web directory and reference them by their names or relative paths.

The idea is fairly simple.

1. Phoenix renders a div with props, slots and handlers as data attributes. In live views these are kept in sync. When SSR is enabled, it also renders the component and inlines the result in the HTML.
2. LiveVue hook mount callback initializes the element. It hooks up all the handlers, injects hook itself so useLiveVue works correctly, and mounts the Vue component.
3. On update, Phoenix only changes data attributes. Hook updates props of the element.
4. On destroy, Vue element is unmounted and garbage collected.

One thing to keep in mind is that hooks are fired only after app.js is fully loaded, so it might cause some delays of the initial render of the component.

LiveVue introduces a number of interesting optimizations:

• Props, Handlers or slots are only send to the client if anything was changed. It's accomplished through a careful modifications of __changed__ assign.
• We use data-props={"#{@props |> Jason.encode()}"} syntax (notice String interpolation) to avoid sending data-props= on each update
• Soon: we'll be sending only updated props
• Soon: we'll be sending only deep-diff of props (similar to LiveJson, but automated)

As explained in the previous section, it takes a moment for Vue component to initialize, even if props are already inlined in the HTML.

It's done only during a "dead" render, without connected socket. It's not needed when doing live navigation - in my experience when using <.link navigate="..."> component is rendered before displaying a new page.

• Add a default handler for Vue emits to eg. automatically push them to the server without explicit v-on handlers.
• try to use Igniter as a way of installing LiveVue in a project
• usePushEvent - an utility similar to useFetch making it easy to get data from &handle_event/3 -> {:reply, data, socket} responses
• useLiveForm - an utility to efforlessly use Ecto changesets & server-side validation, similar to HEEX
• useEventHandler - an utility automatically attaching & detaching handleEvent
• optimize payload - send only json_patch diffs of updated props
• VS code extension higlighting ~V sigil
• Add support for Phoenix streams as props

LiveSvelte