disconnected()

The disconnected hook is called by the disconnectedCallback when an element is removed from the page. Code that needs to run when the element is no longer in the page should be put in disconnected so that you do not need to worry about the rest of the lifecycle (you do not need to use super when implementing disconnected). Code that has both setup and teardown can be simplified using connected since the teardown function has a closure over variables created in connected.

The following example uses disconnected to make an HTTP POST request when the element is removed from the page:

import { StacheElement } from "can";

class MyElement extends StacheElement {
    disconnected() {
        fetch("/api/log", {
            method: "POST",
            body: JSON.stringify({
                msg: "my-el was removed from the page"
            })
        });
    }
}
customElements.define("my-el", MyElement);

const myEl = new MyElement();
document.body.appendChild(myEl);
document.body.removeChild(myEl); // -> POSTs to /api/log