Actions

Actions are how you handle DOM events in your controllers.

<div data-controller="gallery">
  <button data-action="click->gallery#next">…</button>
</div>

// controllers/gallery_controller.js
import { Controller } from "stimulus"

export default class extends Controller {
  next(event) {
    // …
  }
}

An action is a connection between:

a controller method
the controller’s element
a DOM event listener

﹟ Descriptors

The data-action value click->gallery#next is called an action descriptor. In this descriptor:

click is the name of the DOM event to listen for
gallery is the controller identifier
next is the name of the method to invoke

﹟ Event Shorthand

Stimulus lets you shorten the action descriptors for some common element/event pairs, such as the button/click pair above, by omitting the event name:

<button data-action="gallery#next">…</button>

The full set of these shorthand pairs is as follows:

Element	Default Event
a	click
button	click
form	submit
input	input
input type=submit	click
select	change
textarea	input

﹟ Global Events

Sometimes a controller needs to listen for events dispatched on the global window or document objects.

You can append @window or @document to the event name in an action descriptor to install the event listener on window or document, respectively, as in the following example:

<div data-controller="gallery"
     data-action="resize@window->gallery#layout">
</div>

﹟ Options

You can append one or more action options to an action descriptor if you need to specify DOM event listener options.

<div data-controller="gallery"
     data-action="scroll->gallery#layout:!passive">
  <img data-action="click->gallery#open:capture">

Stimulus supports the following action options:

Action option	DOM event listener option
`:capture`	`{ capture: true }`
`:once`	`{ once: true }`
`:passive`	`{ passive: true }`
`:!passive`	`{ passive: false }`

﹟ Event Objects

An action method is the method in a controller which serves as an action’s event listener.

The first argument to an action method is the DOM event object. You may want access to the event for a number of reasons, including:

to read the key code from a keyboard event
to read the coordinates of a mouse event
to read data from an input event
to prevent the browser’s default behavior for an event
to find out which element dispatched an event before it bubbled up to this action

The following basic properties are common to all events:

Event Property	Value
event.type	The name of the event (e.g. `"click"`)
event.target	The target that dispatched the event (i.e. the innermost element that was clicked)
event.currentTarget	The target on which the event listener is installed (either the element with the `data-action` attribute, or `document` or `window`)

The following event methods give you more control over how events are handled:

Event Method	Result
event.preventDefault()	Cancels the event’s default behavior (e.g. following a link or submitting a form)
event.stopPropagation()	Stops the event before it bubbles up to other listeners on parent elements

﹟ Multiple Actions

The data-action attribute’s value is a space-separated list of action descriptors.

It’s common for any given element to have many actions. For example, the following input element calls a field controller’s highlight() method when it gains focus, and a search controller’s update() method every time the element’s value changes:

<input type="text" data-action="focus->field#highlight input->search#update">

When an element has more than one action for the same event, Stimulus invokes the actions from left to right in the order that their descriptors appear.

﹟ Naming Conventions

Always use camelCase to specify action names, since they map directly to methods on your controller.

Avoid action names that simply repeat the event’s name, such as click, onClick, or handleClick:

<button data-action="click->profile#click">Don't</button>

Instead, name your action methods based on what will happen when they’re called:

<button data-action="click->profile#showDialog">Do</button>

This will help you reason about the behavior of a block of HTML without having to look at the controller source.

Next: Targets