Add a Custom Element Extension with the Wix CLI

The Wix CLI makes it easy to add and develop custom element extensions in your app project. These are considered app extensions and appear on the Extensions page in your app's dashboard.

Custom element extensions are built with the web components standard. You define a new HTML tag, which is made available in the Wix editors as a widget.

The Wix CLI creates the necessary files with template code so you can easily start developing your custom element. It also calls define() for you, so you don't need to explicitly call it in your code.

Follow the instructions below to:

1. Add a custom element extension to your app project.
2. Test the custom element on a site.
3. Deploy your app with the custom element.

Step 1 | Add a custom element to your app project

In the terminal:

1. Navigate to your project repo.

2. Run the generate command.

   The CLI displays a menu of extensions to generate. Under Site, select Custom Element and press Enter.

   The CLI then prompts you for the following items:

   • Element name: The name of the element that appears in the <your-widget-name>.extension.ts configuration file. Only you will see this.
   • Element folder: The name of the folder in the project repo that contains the custom element code that the site widget is built on. Only you will see this.

Upon completion, the extension files will be created in your project directory with the following structure:

Learn more about the custom element extension files.

Step 2 | Test your custom element

You can test your custom element while you're developing by running the wix app dev command. Click the editor link that the CLI prints to view your custom element in the editor. This opens your test site editor, where you can view and try it out.

Why do I get a placeholder when previewing my site widget?

In some cases, a placeholder displays when you preview your custom element, even though it displays as expected on a published site.

This can happen if:

• You open the dashboard, site, or editor from the links that the CLI prints. Run the dev command to restart your local environment.
• You preview a site when the site was opened with the editor link. Run the build command and then the release command to release a new version.

Step 3 | Build and deploy your project

Once your app project is ready for production, you can build it and release a version in the app dashboard.

1. Run the build command.

2. Run the release command and follow the prompts to release an app version.

An app version allows you to publish an app to the Wix App Market or install it on a site with a direct install URL. You can view your app versions in the app dashboard.

For more information about building and deploying your app, see Build and Deploy an App with the Wix CLI.

You can control whether your custom element is added to a site automatically when a Wix user installs your app. Set installation.autoAdd to true in your widget's extension file (element.extension.ts) to add the widget to the home page on install. If it's false, the widget isn't added on install. Wix users can add it manually from the editor's Add panel. In the CLI, automatic installation applies only to the home page, not to master pages like the header or footer. For details, configuration examples, and best practices, see About custom element installation with the CLI.

Delete a custom element extension

To delete an existing custom element extension from your app:

1. Delete the folder that contains your custom element's files.
2. Remove the import and .use() statements for the extension from the extensions.ts file.