On Thu, May 7, 2015 at 4:43 PM, Anne van Kesteren <annevk@annevk.nl> wrote: > On Wed, May 6, 2015 at 11:01 PM, Justin Fagnani > <justinfagnani@google.com> wrote: > > How are you supposed to tell if one of your ancestors was removed? > > Is that a hook builtin elements have today? Blink's built-in elements' hook is "inserted into"/"removed from document", including via an ancestor being manipulated as you can see here (this--Node::removedFrom--is the "removed" case): https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit/Source/core/dom/ContainerNode.cpp&sq=package:chromium&type=cs&l=834&rcl=1430970612 This is overridden 68 times by various kinds of nodes including many elements. What it's used for varies; one example is the HTMLMarqueeElement that stops a callback that's driving its animation. If you were trying to implement MARQUEE as a Custom Element, you'd want this callback to call clearTimeout, cancelAnimationFrame, or whatever. There are similar hooks and uses for insertion. The HTML spec itself points to a lot of uses for this; when it switches on things being "in a document" <https://html.spec.whatwg.org/#in-a-document> and something needs to be done/updated/etc. to implement that effect. > > -- > https://annevankesteren.nl/ > >
Received on Thursday, 7 May 2015 08:10:56 UTC