Vite Package Setup

Get started with a Vite Package, setup with TypeScript and Lit


Umbraco recommends building extensions with a setup using TypeScript and a build tool such as Vite. Umbraco uses the library Lit for building web components which we will use throughout this guide.

Getting Started With Vite

Vite comes with a set of good presets to get you quickly up and running with libraries and languages. For example: Lit, Svelte, and Vanilla Web Components with both JavaScript and TypeScript.

Before following this guide, read the Setup Your Development Environment article.

  1. Open a terminal and navigate to the project folder where you want to create your new Vite Package.

  2. Run the following command in the folder to create a new Vite Package:

npm create vite@latest

This command will help you set up your new package, asking you to pick a framework and a compiler.

  1. Enter Client as both the Project Name and Package name when prompted,

For following this tutorial, we recommend using the names given above, although you can choose any other you prefer.

  1. Choose Lit and TypeScript.

Create vite command choices

This creates a new folder called Client, sets up our new project, and creates a package.json file, which includes the necessary packages. This is where all your source files live.

Alternatively of the two steps above, you can type the following:

npm create vite@latest Client -- --template lit-ts

This will create a Vite Package with Lit and TypeScript in a folder called Client.

  1. Navigate to the new project folder Client and install the packages using:

npm install
  1. Install the Backoffice package using the following command:

npm install -D @umbraco-cms/backoffice

Optionally you can use --legacy-peer-deps in the installation command to avoid installing Umbraco´s sub-dependencies like TinyMCE and Monaco Editor: npm install --legacy-peer-deps -D @umbraco-cms/backoffice

If this is used the Intellisense to those external references will not be available.

  1. Create a new file called vite.config.ts in the folder and insert the following code:

import { defineConfig } from "vite";

export default defineConfig({
    build: {
        lib: {
            entry: "src/my-element.ts", // your web component source file
            formats: ["es"],
        outDir: "../App_Plugins/Client", // all compiled files will be placed here
        emptyOutDir: true,
        sourcemap: true,
        rollupOptions: {
            external: [/^@umbraco/], // ignore the Umbraco Backoffice package in the build
    base: "/App_Plugins/Client/", // the base path of the app in the browser (used for assets)

The outDir parameter specifies where the compiled files will be placed. In this case, it is the App_Plugins/Client folder. If you have a different structure such as a Razor Class Library (RCL) project, you should change this path to wwwroot.

This alters the Vite default output into a library mode, where the output is a JavaScript file with the same name as the name attribute in package.json. The name is client.js if you followed this tutorial with no changes.

The source code that is compiled lives in the src folder of your package folder and that is where you can see a my-element.ts file. You can confirm that this file is the one specified as our entry on the Vite config file that we recently created.

The build:lib:entry parameter can accept an array which will allow you to export multiple files during the build. You can read more about Vite's build options here.

Build the ts file in the Client folder so we can use it in our package:

npm run build

Watch for changes and build

If you like to continuously work on the package and have each change built, you can add a watchscript in your package.json with vite build --watch. The example below indicates where in the structure this change should be implemented:

  "name": "Client",
  "scripts": {
    "watch": "vite build --watch"

Then in the terminal, you can run npm run watch.

Umbraco Package declaration

Declare your package to Umbraco via a file called umbraco-package.json. This should be added at the root of your package. In this guide, it is inside the Client/public folder so that Vite automatically copies it over every time it builds.

This example declares a Dashboard as part of your Package, using the Vite example element.

    "$schema": "../../umbraco-package-schema.json",
    "name": "My Dashboard",
    "version": "0.1.0",
    "extensions": [
            "type": "dashboard",
            "alias": "My.Dashboard.MyExtension",
            "name": "My Dashboard",
            "element": "/App_Plugins/Client/client.js",
            "elementName": "my-element",
            "meta": {
                "label": "My Dashboard",
                "pathname": "my-dashboard"

Umbraco needs the name of the element that will render as default when our dashboard loads.

  • This is specified in the manifest as the elementName.

  • Another approach would be to define your default element in the TS code. To do this, in the src/my-element.ts add default to your MyElement class in the file like so:

export default class MyElement extends LitElement {

Learn more about the abilities of the manifest file in the Umbraco Package Manifest article.

Testing your package

To be able to test your package, you will need to run your site.

Before you do this, you need to make sure to run npm run build to compile your TypeScript files and copy them to the App_Plugins/Client folder.

If you try to include some of these resources via Visual Studio (VS), then make sure not to include TypeScript files. Otherwise, VS will try to include a few lines on your .csproj file to compile the TypeScript code that exists in your project folder. When you run your website, VS will try to compile these files and fail.

The final result looks like this:

My dashboard

Back in the src/my-element.ts file, you can update the styles property to make any styling changes. You can change the background-color of the button to white so it is more visible:

button {
    background-color: white;


With this, you have set up your Package and created an Extension for the Backoffice.

In more advanced cases, you can add more elements to your package and create more complex extensions. In that case, you can benefit greatly from creating another project in your solution to hold the files. This way, you can keep your solution clean and organized. We recommend creating a Razor Class Library (RCL) for this purpose. You can read more about this in the Development Flow article.

This Dashboard appears in all sections and does not do much. To extend it to interact with the Umbraco Backoffice, follow the tutorial on Creating Your First Extension.

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