> In a larger Vue.js project, you would likely abstract the Event Bus into a single file, importing it into every component file where it needs to be used. This way, it does not pollute the global namespace.

Instead of having to import a file everywhere, I'm used to add the bus to the Vue prototype:

    // Create a bus for global events
    var busVue = new Vue()

    // vue properties
    Object.defineProperties(Vue.prototype, {
        $bus: {
            get: function () {
                return busVue
            }
        }
    }

so I can simply use it from any Vue component:

    this.$bus.$emit('error', 'Impossible to connect to the database')

for emitting, and for binding on:

    mounted: function (msg) {
        this.$bus.$on('error', this.alert)
    }