Vue Router installation and setup - Performance & Optimization

Performance: Vue Router installation and setup

MEDIUM IMPACT

This affects the initial page load speed and navigation responsiveness by adding routing logic and components to the Vue app.

Setting up routing in a Vue app

Vue

import { createApp } from 'vue';
import { createRouter, createWebHistory } from 'vue-router';
import App from './App.vue';
import Home from './components/Home.vue';
import About from './components/About.vue';

const routes = [
  { path: '/', component: Home },
  { path: '/about', component: About }
];

const router = createRouter({
  history: createWebHistory(),
  routes
});

const app = createApp(App);
app.use(router);
app.mount('#app');

Client-side routing avoids full page reloads, improving navigation speed and reducing server requests.

📈 Performance GainReduces LCP and INP by enabling fast client-side route changes without reloads.

Setting up routing in a Vue app

Vue

import { createApp } from 'vue';
import App from './App.vue';

const app = createApp(App);
app.mount('#app');

No routing setup means full page reloads on navigation, causing slower user experience and higher server load.

📉 Performance CostTriggers full page reloads on navigation, increasing LCP and INP.

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
No Router (full reloads)	High (full page reload)	Many (full page layout)	High (full repaint)	[X] Bad
Vue Router with eager loading	Moderate (component swaps)	Few (component layout changes)	Moderate (partial repaint)	[!] OK
Vue Router with lazy loading	Low (only loaded components)	Few (minimal layout)	Low (minimal repaint)	[OK] Good

Rendering Pipeline

Vue Router intercepts navigation events and updates the Vue component tree without reloading the page, affecting the rendering pipeline by triggering component re-renders and DOM updates.

→JavaScript Execution

→Virtual DOM Update

→Layout

→Paint

⚠️ BottleneckVirtual DOM Update and Layout when switching routes with large components

Core Web Vital Affected

LCP, INP

This affects the initial page load speed and navigation responsiveness by adding routing logic and components to the Vue app.

Optimization Tips

1Use Vue Router to avoid full page reloads and improve navigation speed.

2Implement lazy loading for route components to reduce initial bundle size.

3Monitor route changes in DevTools Performance tab to identify rendering bottlenecks.

Performance Quiz - 3 Questions

What is the main performance benefit of using Vue Router instead of full page reloads?

A Less JavaScript execution overall

B Smaller initial bundle size

C Faster navigation by avoiding full page reloads

D No DOM updates needed

DevTools: Performance

How to check: Open DevTools Performance tab, record navigation between routes, and observe scripting and rendering times.

What to look for: Look for reduced scripting and layout times during route changes indicating efficient client-side routing.

Practice

1. What is the main purpose of Vue Router in a Vue application?

easy

A. To manage navigation between different pages or views

B. To style components with CSS

C. To handle data fetching from APIs

D. To compile Vue components into JavaScript

Solution

1. Step 1: Understand Vue Router's role

   Vue Router is designed to help Vue apps navigate between different pages or views smoothly.

2. Step 2: Compare with other options

   Styling, data fetching, and compiling are handled by other tools, not Vue Router.

3. Final Answer:

   To manage navigation between different pages or views -> Option A

4. Quick Check:

   Vue Router = Navigation [OK]

Hint: Vue Router controls page navigation in Vue apps [OK]

Common Mistakes:

• Confusing Vue Router with styling or data fetching tools
• Thinking Vue Router compiles components
• Assuming Vue Router manages state

2. Which of the following is the correct way to install Vue Router in a Vue 3 project using npm?

easy

A. npm install vue-router@3

B. npm install vue-router@4

C. npm install vue-router@2

D. npm install vue-router@5

Solution

1. Step 1: Identify Vue Router version for Vue 3

   Vue 3 uses Vue Router version 4, so you must install vue-router@4.

2. Step 2: Check other versions

   Versions 2 and 3 are for Vue 2 or earlier, and version 5 does not exist yet.

3. Final Answer:

   npm install vue-router@4 -> Option B

4. Quick Check:

   Vue 3 uses Vue Router 4 [OK]

Hint: Vue 3 pairs with vue-router version 4 [OK]

Common Mistakes:

• Installing older Vue Router versions for Vue 3
• Using a non-existent version number
• Forgetting to specify version for compatibility

3. Given this Vue Router setup code, what will be the rendered output when navigating to '/about'?

import { createRouter, createWebHistory } from 'vue-router';
import Home from './components/Home.vue';
import About from './components/About.vue';

const routes = [
  { path: '/', component: Home },
  { path: '/about', component: About }
];

const router = createRouter({
  history: createWebHistory(),
  routes
});

export default router;

And in App.vue template:

<router-view />

medium

A. The Home component content is shown

B. An error occurs because routes are missing

C. Nothing is shown because router is not used

D. The About component content is shown

Solution

1. Step 1: Understand route matching

   When the URL is '/about', Vue Router matches the route with path '/about' and renders the About component.

2. Step 2: Check router-view usage

   The <router-view /> in App.vue displays the matched component, so About content appears.

3. Final Answer:

   The About component content is shown -> Option D

4. Quick Check:

   URL '/about' shows About component [OK]

Hint: URL path matches route, router-view shows that component [OK]

Common Mistakes:

• Assuming Home shows for all paths
• Forgetting router-view renders matched component
• Thinking router must be manually mounted in template

4. What is wrong with this Vue Router setup code?

import { createRouter, createWebHistory } from 'vue-router';
import Home from './components/Home.vue';
import Contact from './components/Contact.vue';

const routes = [
  { path: '/', component: Home },
  { path: '/contact', component: Contact }
];

const router = createRouter({
  history: createWebHistory,
  routes
});

export default router;

medium

A. Components Home and Contact are not imported

B. Routes array is empty

C. createWebHistory is missing parentheses when used

D. Router is not created with createRouter function

Solution

1. Step 1: Check createWebHistory usage

   createWebHistory is a function and must be called with parentheses: createWebHistory()

2. Step 2: Verify other parts

   Routes are defined with imported components, router is created correctly.

3. Final Answer:

   createWebHistory is missing parentheses when used -> Option C

4. Quick Check:

   Functions need parentheses to execute [OK]

Hint: Call createWebHistory() with () to avoid errors [OK]

Common Mistakes:

• Forgetting parentheses on createWebHistory
• Believing routes array is empty
• Misnaming createRouter function

5. You want to add a navigation menu with links to Home and About pages using Vue Router. Which template code correctly uses Vue Router components for navigation?

hard

A.
Home
About

B.
Home
About

C.
Home
About

D.
Home
About

Solution

1. Step 1: Use correct attribute for router-link

   The correct attribute to specify the route path is 'to', not 'href'.

2. Step 2: Use correct path format

   Paths must start with '/', so '/about' is correct, while 'about' without slash is incorrect.

3. Final Answer:

   Use <router-link to="/"> and <router-link to="/about"> with router-view -> Option A

4. Quick Check:

   router-link uses 'to' with leading slash paths [OK]

Hint: Use 'to' attribute with leading slash in router-link [OK]

Common Mistakes:

• Using 'href' instead of 'to' in router-link
• Omitting leading slash in paths
• Using plain anchor tags instead of router-link