ToggleEvent sourceThe source property of a ToggleEvent object is the element which triggered the toggle event to fire for a popover, <dialog>, or <details> element, if applicable.htmlHTMLnewly2026-05-11https://html.spec.whatwg.org/multipage/interaction.html#dom-toggleevent-sourcehttps://developer.mozilla.org/docs/Web/API/ToggleEvent/sourceapi.ToggleEvent.sourcehttps://nowyoucanuse.com/features--toggleevent-source.html