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Using Stimulus

In a decision to move Nepenthes towards the Hotwire approach, we introduced Stimulus.js to replace a collection of dynamically loaded custom JavaScript files used to sprinkle some interactivity.

This guide will outline how to add controllers and the conventions around it. This is not a documentation of stimulus itself. Use their documentation instead:

Adding controllers

All controllers live under frontend/src/stimulus/controllers/. The naming convention is <controller-name>.controller.ts, meaning to dasherize the name of the controller. This makes it easier to generate names and classes using common IDEs.

If you want to add a common pattern, manually register the controller under frontend/src/stimulus/setup.ts. Often you'll want to have a dynamically loaded controller instead though.

Dynamically loaded controllers

To dynamically load a controller, it needs to live under frontend/src/stimulus/controllers/dynamic/<controller-name>.controller.ts.

In DOM, you'll tell the application the controller is dynamically loaded using the data-application-target="dynamic"attribute. It tells the application controller (frontend/src/stimulus/controllers/op-application.controller.ts) we load on every page on body to dynamically import and load the controller named users.

<div data-controller="users" data-application-target="dynamic"></div>

Namespacing dynamic controllers

If you want to organize your dynamic controllers in a subfolder, use the double dash convention of stimulus. For example, adding a new admin controller settings, you'd do the following:

  1. Add the controller under frontend/src/stimulus/controllers/dynamic/admin/settings.controller.ts
  2. Specify the controller name with a double dash for each folder
<div data-controller="admin--settings" data-application-target="dynamic"></div>

You need to take care to prefix all actions, values etc. with the exact same pattern, e.g., data-admin--settings-target="foobar".

Requiring a page controller

If you have a single controller used in a partial, we have added a helper to use in a partial in order to append a controller to the #contenttag. This is useful if your template doesn't have a single DOM root. For example, to load the dynamic project-storage-form controller and provide a custom value to it:

<% content_controller 'project-storage-form',
                      dynamic: true,
                      'project-storage-form-folder-mode-value': @project_storage.project_folder_mode %>