Add login to bookshop Vue.js app (#358)

bookshop/app/vue/app.js

@@ -10,7 +10,7 @@ const books = Vue.createApp ({
         list: [],
         book: undefined,
         order: { quantity:1, succeeded:'', failed:'' },
-        user: {}
+        user: undefined
       }
     },
 
@@ -42,19 +42,25 @@ const books = Vue.createApp ({
             }
         },
 
-        async fetchUserInfo() {
+        async login() {
             try {
-                const { data } = await axios.get('/user/me')
-                books.user = data
+                const { data:user } = await axios.post('/user/login',{})
+                if (user.id !== 'anonymous') books.user = user
             } catch (err) { books.user = { id: err.message } }
-        }
+        },
+
+        async getUserInfo() {
+            try {
+                const { data:user } = await axios.get('/user/me')
+                if (user.id !== 'anonymous') books.user = user
+            } catch (err) { books.user = { id: err.message } }
+        },
     }
 }).mount("#app")
 
-// initially fill list of books
-books.fetch()
+books.getUserInfo()
+books.fetch() // initially fill list of books
 
-books.fetchUserInfo()
 document.addEventListener('keydown', (event) => {
     // hide user info on request
     if (event.key === 'u')  books.user = undefined