What is routerLink and routerLinkActive in Angular

Q: What is routerLink in Angular?

routerLink is a directive in Angular used to define navigation routes without reloading the page.

Q: What does routerLinkActive do?

It adds a CSS class to elements when their corresponding route is active in the Angular app.

💡 Concept Name

routerLink & routerLinkActive – Angular directives used for navigation and styling active links in single-page applications.

📘 Quick Intro

routerLink is used to bind a route path to an anchor tag without a page reload. routerLinkActive adds a CSS class to an element when its route becomes active.

🧠 Analogy / Short Story

Imagine you're navigating tabs on a dashboard. routerLink moves you to a new tab, and routerLinkActive highlights the current tab you’re viewing.

🔧 Technical Explanation

🔗 routerLink: Replaces traditional href for SPA routing.
🎨 routerLinkActive: Applies CSS classes to highlight active links.
⚙️ Works with RouterModule and Angular’s routing engine.
📦 Can be used with routerLinkActiveOptions for exact match.
🌐 Enables navigation within Angular components and modules.

🎯 Purpose & Use Case

✅ Create client-side navigation in SPAs.
✅ Visually indicate active navigation items in a navbar.
✅ Avoid full page reloads while routing.

💻 Real Code Example

<a routerLink="/dashboard" routerLinkActive="active">Dashboard</a>

<a [routerLink]="['/user', userId]" 
   routerLinkActive="active" 
   [routerLinkActiveOptions]="{ exact: true }">
   User Profile
</a>

❓ Interview Q&A

Q1: What is routerLink in Angular?
A: A directive that defines navigation routes without reloading the page.

Q2: What does routerLinkActive do?
A: It applies a CSS class to an element when its route is active.

Q3: Can routerLink take dynamic values?
A: Yes, using property binding syntax like [routerLink].

Q4: What’s the default behavior of routerLinkActive?
A: It matches any sub-route unless routerLinkActiveOptions is set to exact.

Q5: Is routerLink a replacement for href in Angular?
A: Yes, for routing inside Angular apps.

📝 MCQs

Q1. What does routerLink do?

Triggers a reload
Applies styles
Navigates to a route without reloading
Disables navigation

Q2. What is the purpose of routerLinkActive?

Removes links
Adds title
Applies CSS class when route is active
Reloads component

Q3. What attribute is used for exact route match?

routerOptions
exactRoute
routerLinkActiveOptions
matchRoute

Q4. Can routerLink take array input?

Yes
No
Only in forms
Only in services

Q5. Which directive replaces traditional href?

routerPath
routerLink
ngRoute
linkRef

Q6. What CSS class is added by routerLinkActive by default?

default
active-link
active
Specified by developer

Q7. What module is required to use routerLink?

FormsModule
HttpClientModule
RouterModule
CoreModule

Q8. Does routerLink reload the page?

Yes
Sometimes
Only for POST
No

Q9. How does Angular know a route is active?

It checks headers
It listens to clicks
By comparing URL with route path
It polls DOM

Q10. Which option ensures exact match for route?

{ route: exact }
{ active: true }
{ exact: true }
{ strict: true }

💡 Bonus Insight

Use routerLinkActive on parent elements (like <li>) to highlight entire menu items. Combine it with Angular animations for smoother navigation UI.

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