enable arrow key navigation

src/App.vue

@@ -51,6 +51,12 @@ export default {
     updateRoute () {
       this.$router.push(`/${this.where}/${this.when}`)
       window.localStorage.setItem('where', this.where)
+    },
+    previousDay () {
+      this.when === 1 ? this.when = 6 : this.when--
+    },
+    nextDay () {
+      this.when === 6 ? this.when = 1 : this.when++
     }
   },
   filters: {
@@ -65,6 +71,18 @@ export default {
   },
   created () {
     this.where = window.localStorage.getItem('where') || 'zentralmensa'
+    let vm = this
+    document.onkeydown = (evt) => {
+      evt = evt || window.event
+      switch (evt.keyCode) {
+        case 37:
+          vm.previousDay()
+          break
+        case 39:
+          vm.nextDay()
+          break
+      }
+    }
   }
 }
 </script>