CloseWatcher: cancel event
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
A cancel
event is fired at a 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 Esc key) as well as CloseWatcher.requestClose()
.
Syntax
Use the event name in methods like addEventListener()
, or set an event handler property.
addEventListener("cancel", (event) => { })
oncancel = (event) => { }
Event type
An 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 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
Specification |
---|
HTML Standard # handler-closewatcher-oncancel |
Browser compatibility
BCD tables only load in the browser