disconnect()

Calling disconnect will clean up an element's event handlers and call its disconnected hook. Normally this is called by the disconnectedCallback, but can be called manually for testing:

import { StacheElement } from "can/everything";

const logs = [];

class MyElement extends StacheElement {
    static view = `
        <p>{{this.name}} has been running for {{this.time}} seconds</p>
    `;

    static props = {
        name: { type: String, default: "App" },
        time: { type: Number, default: 0 }
    };

    connected() {
        this.listenTo("name", (ev, newName) => {
            logs.push(`name change to ${newName}`);
        });

        let intervalId = setInterval(() => {
            this.time++;
        }, 1000);

        return () => {
            clearInterval(intervalId);
        };
    }

    disconnected() {
        logs.push("disconnected");
    }
}
customElements.define("my-el", MyElement);

const myEl = new MyElement()
    .connect();

myEl.innerHTML; // -> <p>App has been running for 0 seconds</p>

myEl.name = "Counter";
logs; // -> [ "name changed to Counter" ]
myEl.innerHTML; // -> <p>Counter has been running for 0 seconds</p>

// ...some time passes
myEl.innerHTML; // -> <p>Counter has been running for 3 seconds</p>

myEl.disconnect();
myEl.innerHTML; // -> <p>Counter has been running for 3 seconds</p>

myEl.name = "Stopped Counter";
logs; // -> [ "name changed to Counter", "disconnected" ]

// ...some time passes
myEl.innerHTML; // -> <p>Stopped Counter has been running for 3 seconds</p>