aem-svelte

A bare-bones example how to use Svelte with Rollup in Adobe Experience Manager

Credits to https://medium.com/@jlanssie/use-svelte-in-adobe-experience-manager-ec51bb3494c5 and https://typeofnan.dev/how-to-set-up-a-svelte-app-with-rollup/

Project Setup

Add Svelte modules

Go to your ui.frontend module root.

Install Svelte

npm i svelte

and the Rollup libraries

npm i @rollup/plugin-node-resolve rollup-plugin-svelte --save-dev

• @rollup/plugin-node-resolve is used to help rollup resolve third-party plugins
• rollup-plugin-svelte is a third-party plugin that helps rollup understand how to process Svelte apps

Create the Rollup Config File

rollup.config.js

import svelte from 'rollup-plugin-svelte';
import resolve from '@rollup/plugin-node-resolve';

export default
{
  input: 'src/index.js',
  output: {
    file: '../ui.apps/src/main/content/jcr_root/apps/aem-svelte/clientlibs/clientlib-site/js/bundle.js',
    format: 'iife',
    name: 'bundle',
  },
  plugins: [
    svelte(),
    resolve({ browser: true }),
  ],
};

Add aemsync to push content to AEM upon a file change.

npm i aemsync concurrently --save-dev

with all the steps above your package.json should look like

{
  "name": "aem-svelte",
  "author": "Yegor Kozlov",
  "version": "1.0.0",
  "dependencies": {
    "svelte": "^4.2.3"
  },
  "scripts": {
    "build": "rollup -c",
    "dev": "concurrently \"rollup -c -w\" \"aemsync -w ../ui.apps/src/main/content\""
  },
  "devDependencies": {
    "@rollup/plugin-node-resolve": "^15.3.0",
    "aemsync": "^5.0.5",
    "concurrently": "^9.1.0",
    "rollup": "^4.27.4",
    "rollup-plugin-svelte": "^7.2.2"
  }
}

Create Svelte components

counter.svelte

<script>
  import { count } from './store.js';
  export let message;

	export function increment() {
		count.update(n => n + 1);
	}
</script>

<button on:click={increment}>
	{message} clicked {$count}
	{$count === 1 ? 'time' : 'times'}
</button>

The counter value is managed in a Svelte store and can be used by other components:

store.js

// store.js
// eslint-disable-next-line import/no-unresolved
import { writable } from 'svelte/store';

export const count = writable(0);

Create a Registry of Svelte components

registry.js

We will need it to resolve components by name

import Counter from './counter.svelte';

const COMPONENTS = {
  counter: Counter
};

export default COMPONENTS;

Initialize Svelte components

This JavaScript file will handle all our components’ registration, creation mounting and it will make sure that newly added components to the page get picked up, even after the DOM has loaded.

import COMPONENTS from './registry';

class SvelteComponent extends HTMLElement {
  connectedCallback() {
    const props = this.dataset;
    const clz = COMPONENTS[props.component];
    if(!clz) {
      throw new Error(`Component ${props.component} not found. Known components: ${Object.keys(COMPONENTS).join(', ')}`);
    }
    new clz({ target: this, props });
  }
}

customElements.define('svelte-component', SvelteComponent);

Create AEM Component

The AEM component will create an HTML element with the tag and an attribute data-component set from the component properties.

<svelte-component data-component="counter"></svelte-component>

the component name counter must match the key in registry.js

How to Develop

Build and deploy the project

mvn clean install -PautoInstallPackage

Start the Dev mode to watch for changes and push them to AEM

from the ui.frontend directory run

npm run dev

you should see something like

> aem-svelte@1.0.0 dev
> concurrently "rollup -c -w" "aemsync -w ../ui.apps/src/main/content"

[1] aemsync version 5.0.5
[1]
[1]     Watch over: /Users/yegor.kozlov/projects/scratchpad/aem-svelte/ui.apps/src/main/content
[1]        Targets: http://admin:admin@localhost:4502
[1]        Exclude: **/jcr_root/*
[1]                 **/@(.git|.svn|.hg|target)
[1]                 **/@(.git|.svn|.hg|target)/**
[1]          Delay: 300
[1]
[0] rollup v4.27.4
[0] bundles src/index.js → ../ui.apps/src/main/content/jcr_root/apps/aem-svelte/clientlibs/clientlib-site/js/bundle.js...
[0] created ../ui.apps/src/main/content/jcr_root/apps/aem-svelte/clientlibs/clientlib-site/js/bundle.js in 170ms
[1] + jcr_root/apps/aem-svelte/clientlibs/clientlib-site/js/bundle.js

The navigate to the counter page http://localhost:4502/content/aem-svelte/counter.html?wcmmode=disabled and you should see your Svelte component in action.

All changes made in the ui.fronentend module will be compiled and push to AEM.