observer.js

class Observer {
    register(a) {
        if (this.array == null) {
            this.array = [];
        }
        this.array.push(a);
    }

    unregister() {
        this.array = []
    }

    notice(b) {
        for (let x of this.array) {
            x.notice(b);
        }
    }
}
let observer = new Observer()
export default { observer }