✨ (new version) display button if there is a new version.

src/components/NewVersion.vue

@@ -0,0 +1,32 @@
+<template>
+  <aside class="new-version" v-if="hasNewVersion">
+    <button class="button is-primary" @click="reload">
+      new version available
+    </button>
+  </aside>
+</template>
+
+<script lang="ts">
+import { serviceWorkerBusEvent } from '@/bus/serviceWorkerEventBus'
+import { defineComponent, onMounted, ref } from 'vue'
+
+export default defineComponent({
+  name: 'NewVersion',
+  setup() {
+    const hasNewVersion = ref(false)
+    onMounted(() => {
+      serviceWorkerBusEvent.addEventBusListener(
+        () => {
+          hasNewVersion.value = true
+        },
+        {
+          once: true,
+          retro: true
+        }
+      )
+    })
+
+    return { hasNewVersion, reload: () => location.reload() }
+  }
+})
+</script>