AbortController

#include <Ultralight/dom/EventListener.h>

Overview

A controller that removes a group of DOM event listeners together.

An AbortController provides an AbortSignal that can be shared across multiple event listeners. Calling abort() removes every listener registered with that signal at once, without needing to keep individual EventListener handles.

Pass the controller's signal to each listener:

dom::AbortController drag;
document.addEventListener("mousemove", OnDrag, { .signal = drag.signal() });
document.addEventListener("mouseup", OnDrop, { .signal = drag.signal() });
 
// Later:
drag.abort();

Tying Listeners to an Object

A callback that captures this lives as long as the page. Unlike on the web, destroying an AbortController aborts it automatically.

You should store a controller as a class member so its listeners stop firing when the owning object is destroyed:

class Hud {
 public:
  explicit Hud(dom::Document document) {
    document.getElementById("close").addEventListener(
        "click", [this] { CloseHud(); }, { .signal = listeners_.signal() });
  }
 
 private:
  void CloseHud() {}
  dom::AbortController listeners_;
};

Replacing a Controller

An AbortController aborts only once. After aborting, its signal stays aborted and won't add new listeners.

To start over, assign a fresh controller to the variable (the old controller aborts first):

drag = dom::AbortController();

Note

Once its signal has added a listener, you must abort, destroy, or assign over the controller on the Renderer's thread.

See also

dom::AbortSignal, dom::AddEventListenerOptions, dom::EventListener

Public Member Functions
	AbortController ()
	Create a controller that hasn't aborted.
	AbortController (const AbortController &)=delete
AbortController &	operator= (const AbortController &)=delete
	AbortController (AbortController &&other) noexcept=default
	Move constructor (other becomes empty, and its signal() then returns a signal that never aborts).
AbortController &	operator= (AbortController &&other) noexcept
	Move assignment (aborts this controller, then takes over other's signal).
	~AbortController ()
	Destroy this controller and abort it.
AbortSignal	signal () const
	Get the signal to pass in AddEventListenerOptions (signal).
void	abort ()
	Remove every listener added with this controller's signal (abort).

Constructor & Destructor Documentation

AbortController() [1/3]

AbortController ( )

inline

Create a controller that hasn't aborted.

AbortController() [2/3]

AbortController ( const AbortController & )

delete

AbortController() [3/3]

AbortController ( AbortController && other )

defaultnoexcept

Move constructor (other becomes empty, and its signal() then returns a signal that never aborts).

Parameters

other

The AbortController to move from.

~AbortController()

~AbortController ( )

inline

Destroy this controller and abort it.

Member Function Documentation

abort()

void abort ( )

inline

Remove every listener added with this controller's signal (abort).

After this, signal().aborted() returns true and listeners added with the signal are never added. Calling it again does nothing. Safe to call from inside a listener's callback.

operator=() [1/2]

AbortController & operator= ( AbortController && other )

inlinenoexcept

Move assignment (aborts this controller, then takes over other's signal).

Parameters

other

The AbortController to move from.

Returns

Returns this AbortController.

operator=() [2/2]

AbortController & operator= ( const AbortController & )

delete

signal()

AbortSignal signal ( ) const

inline

Get the signal to pass in AddEventListenerOptions (signal).

Returns

Returns this controller's signal. Every call returns the same signal.

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The documentation for this class was generated from the following file:

• Ultralight/dom/EventListener.h