vue-event-bus.js

// global Event Bus
const eventBus = new Vue();

/* ... */

// some deeply nested component
methods: {
  onClick() {
    // emit a custom event on the Event Bus, not on "this" component
    eventBus.$emit('save');
  }
}

/* ... */

// any other component
mounted() {
  // subscribe to event on the Event Bus
  eventBus.$on('save', () => {/**/});
}