events.js

export class EventRegister {
    constructor(...args) {
        this.callbacks = [];
        args.forEach(arr => this.add.apply(this, arr));
    }

    add(target, event, callback) {
        this.callbacks.push([target, event, callback]);
        target.addEventListener(event, callback);
    }

    remove(target, event, callback) {
        target.removeEventListener(event, callback);
    }

    dispose() {
        this.callbacks.forEach(arr => {
            target.remove.apply(this, arr);
        })
    }
}


// Usage
class SomeElement extends LitElement {
    connectedCallback() {
        super.connectedCallback();

        this.eventRegister = new EventRegister(
            [window, 'login', (e) => this.user = e.detail],
            [window, 'logout', (e) => this.user = null]
        )
    }

    disconnectedCallback() {
        super.disconnectedCallback();
        this.eventRegister.dispose();
    }
}