How to display a “loading” animation while a lazy-loaded route component is being loaded?

You can use navigation guards to activate/deactivate a loading state that shows/hides a loading component:

If you would like to use something like “nprogress” you can do it like this:

http://jsfiddle.net/xgrjzsup/2669/

const router = new VueRouter({
  routes
})

router.beforeEach((to, from, next) => {
  NProgress.start()
  next()
})
router.afterEach(() => {
  NProgress.done()
})

Alternatively, if you want to show someting in-place:

http://jsfiddle.net/h4x8ebye/1/

Vue.component('loading',{ template: '<div>Loading!</div>'})

const router = new VueRouter({
  routes
})

const app = new Vue({
  data: { loading: false },
  router
}).$mount('#app')

router.beforeEach((to, from, next) => {
  app.loading = true
    next()
})

router.afterEach(() => {
  setTimeout(() => app.loading = false, 1500) // timeout for demo purposes
})

Then in the template:

<loading v-if="$root.loading"></loading>
  <router-view v-else></router-view>

That could also be easily encapsulated in a very small component instead of using the $root component for the loading state.