Programmatic navigation with useRouter in Vue - Performance & Optimization

Performance: Programmatic navigation with useRouter

MEDIUM IMPACT

This affects page navigation speed and user interaction responsiveness when changing routes programmatically.

Navigating between pages on user action

Vue

const router = useRouter();
function goToPage() {
  router.push('/page2');
}

Only one route change is triggered, reducing unnecessary renders and improving responsiveness.

📈 Performance Gainsingle route change, faster interaction response

Navigating between pages on user action

Vue

const router = useRouter();
function goToPage() {
  router.push('/page1');
  router.push('/page2');
}

Triggering multiple route changes in quick succession causes redundant renders and blocks user interaction.

📉 Performance Costblocks rendering for 100+ms due to multiple route changes

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Multiple rapid router.push calls	High (many DOM updates)	Multiple reflows	High paint cost	[X] Bad
Single router.push call	Low (one DOM update)	Single reflow	Low paint cost	[OK] Good

Rendering Pipeline

Programmatic navigation triggers route changes that cause the framework to update the DOM and re-render components for the new page.

→JavaScript Execution

→Layout

→Paint

→Composite

⚠️ BottleneckJavaScript Execution and Layout due to component re-rendering

Core Web Vital Affected

INP

This affects page navigation speed and user interaction responsiveness when changing routes programmatically.

Optimization Tips

1Avoid calling router.push multiple times in a row.

2Batch or debounce navigation calls to reduce re-renders.

3Use programmatic navigation only when necessary to improve INP.

Performance Quiz - 3 Questions

What is the main performance risk of calling router.push multiple times quickly?

A It improves page load speed.

B It causes multiple re-renders and blocks user interaction.

C It reduces bundle size.

D It decreases memory usage.

DevTools: Performance

How to check: Record a session while triggering programmatic navigation. Look for multiple layout and paint events caused by route changes.

What to look for: Check for long scripting times and multiple reflows indicating redundant route changes.

Practice

1. What does the useRouter function provide in a Vue 3 component?

easy

A. A method to style components dynamically

B. A way to fetch data from an API

C. Access to the router instance to navigate programmatically

D. A tool to manage component state

Solution

1. Step 1: Understand the purpose of useRouter

   useRouter is a Vue Router composable that gives access to the router instance inside setup functions.

2. Step 2: Identify what the router instance allows

   The router instance allows programmatic navigation, such as using router.push() to change routes.

3. Final Answer:

   Access to the router instance to navigate programmatically -> Option C

4. Quick Check:

   useRouter = router access [OK]

Hint: Remember: useRouter gives router control inside components [OK]

Common Mistakes:

• Thinking useRouter fetches data
• Confusing useRouter with state management
• Assuming useRouter styles components

2. Which of the following is the correct syntax to navigate to the '/home' route using useRouter in Vue 3?

easy

A. const router = useRouter(); router.change('/home');

B. const router = useRouter(); router.push('/home');

C. const router = useRouter(); router.navigate('/home');

D. const router = useRouter(); router.go('/home');

Solution

1. Step 1: Recall the method to change routes programmatically

   The correct method to navigate is router.push().

2. Step 2: Match the syntax with the correct method

   Only router.push('/home') is valid; other methods like go, navigate, or change do not exist on the router instance.

3. Final Answer:

   const router = useRouter(); router.push('/home'); -> Option B

4. Quick Check:

   router.push() navigates routes [OK]

Hint: Use router.push() to navigate routes programmatically [OK]

Common Mistakes:

• Using router.go() instead of router.push()
• Trying router.navigate() which is invalid
• Calling router.change() which doesn't exist

3. Consider this Vue 3 setup code snippet:

import { useRouter } from 'vue-router';
export default {
  setup() {
    const router = useRouter();
    function goToProfile() {
      router.push({ name: 'profile', params: { userId: 42 } });
    }
    return { goToProfile };
  }
}

What happens when goToProfile() is called?

medium

A. The app reloads the current page

B. Nothing happens because router.push requires a string path

C. An error occurs because params cannot be passed this way

D. The app navigates to the route named 'profile' with userId 42 as a parameter

Solution

1. Step 1: Understand router.push with named routes and params

   Using router.push({ name: 'profile', params: { userId: 42 } }) navigates to the route named 'profile' and passes the parameter userId=42.

2. Step 2: Confirm this is valid syntax and behavior

   This is the correct way to navigate to a named route with parameters in Vue Router.

3. Final Answer:

   The app navigates to the route named 'profile' with userId 42 as a parameter -> Option D

4. Quick Check:

   router.push({name, params}) navigates with params [OK]

Hint: Use object with name and params in router.push() for named routes [OK]

Common Mistakes:

• Thinking params can't be passed as object
• Assuming router.push only accepts string paths
• Confusing params with query parameters

4. Identify the error in this Vue 3 setup function using useRouter:

import { useRouter } from 'vue-router';
export default {
  setup() {
    const router = useRouter;
    function goHome() {
      router.push('/home');
    }
    return { goHome };
  }
}

medium

A. useRouter is not called as a function, missing parentheses

B. router.push should use an object, not a string

C. goHome function is not returned from setup

D. router.push is not a valid method

Solution

1. Step 1: Check how useRouter is assigned

   The code assigns const router = useRouter; without parentheses, so router is a reference to the function, not the router instance.

2. Step 2: Understand the impact on router.push call

   Since router is not the router instance, calling router.push() will cause an error because router is not an object with push method.

3. Final Answer:

   useRouter is not called as a function, missing parentheses -> Option A

4. Quick Check:

   Call useRouter() with () to get router instance [OK]

Hint: Always call useRouter() with parentheses to get router [OK]

Common Mistakes:

• Forgetting parentheses after useRouter
• Using string instead of object incorrectly (not error here)
• Not returning functions from setup (actually returned here)

5. You want to redirect users to the login page if they are not authenticated after clicking a button. Which Vue 3 setup code correctly uses useRouter for this programmatic navigation?

hard

A. const router = useRouter(); function checkAuth() { if (!isAuthenticated) router.push('/login'); }

B. const router = useRouter; function checkAuth() { if (!isAuthenticated) router.push('/login'); }

C. const router = useRouter(); function checkAuth() { if (!isAuthenticated) router.go('/login'); }

D. const router = useRouter(); function checkAuth() { if (!isAuthenticated) router.navigate('/login'); }

Solution

1. Step 1: Confirm correct useRouter call

   const router = useRouter(); function checkAuth() { if (!isAuthenticated) router.push('/login'); } correctly calls useRouter() with parentheses to get the router instance.

2. Step 2: Verify correct navigation method

   const router = useRouter(); function checkAuth() { if (!isAuthenticated) router.push('/login'); } uses router.push('/login'), which is the correct method to navigate programmatically.

3. Final Answer:

   const router = useRouter(); function checkAuth() { if (!isAuthenticated) router.push('/login'); } -> Option A

4. Quick Check:

   Call useRouter() and use router.push() for navigation [OK]

Hint: Call useRouter() and use router.push() to redirect [OK]

Common Mistakes:

• Not calling useRouter as a function
• Using router.go() or router.navigate() which don't exist
• Forgetting to check authentication before navigation