CloseWatcher: cancel event

{{APIRef("HTML DOM")}}

A cancel event is fired at a {{domxref("CloseWatcher")}} object before the close event, so that close can be prevented from firing, if necessary. It is triggered by all close signals (e.g., the <kbd>Esc</kbd> key) as well as {{domxref("CloseWatcher.requestClose()")}}.

Syntax

Use the event name in methods like {{domxref("EventTarget.addEventListener", "addEventListener()")}}, or set an event handler property.

addEventListener("cancel", (event) => { })

oncancel = (event) => { }

Event type

An {{domxref("Event")}}.

Examples

Using the cancel event

In this example, we ask the user to confirm that they really want to close the component, and if they don't, we cancel the event using {{domxref("Event.preventDefault()")}}, which prevents the close event from being fired.

watcher.addEventListener("cancel", (e) => {
  if (e.cancelable && hasUnsavedData) {
    const userReallyWantsToClose = confirm("Are you sure you want to close?");
    if (!userReallyWantsToClose) {
      e.preventDefault();
    }
  }
});

// Trigger a close request manually
watcher.requestClose();

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}