router-outlet and it's purpose

Understanding <router-outlet> in Angular and Its Purpose

In Angular, the <router-outlet> directive plays an important role in navigation and showing components dynamically based on the router configuration of the application. Let's see more about its purpose, how it works, and a few advanced use examples.

What is <router-outlet>?

<router-outlet> is an Angular built-in directive used as a placeholder for dynamically loaded routed components based on the application's router configuration. It acts as a viewport where Angular inserts the content of the active route.

Purpose of <router-outlet>

• Dynamic Component Loading: It allows Angular to render different components based on the URL path.
• Single Page Application (SPA): It helps build SPAs by loading only those parts of a page that are needed without reloading it entirely.
• Supports Nested Routing: Multiple <router-outlet> elements can be used to create child routes and complex navigation structures.
• Smooth Transitions: Enables seamless navigation between views without requiring a page refresh.

How <router-outlet> Works

Step 1: Define Routes in app-routing.module.ts

import { NgModule } from "@angular/core";  
import { RouterModule, Routes } from "@angular/router";  
import { HomeComponent } from "./home/home.component";  
import { AboutComponent } from "./about/about.component";  

const routes: Routes = [  
  { path: "", component: HomeComponent },  
  { path: "about", component: AboutComponent }  
];  

@NgModule({  
  imports: [RouterModule.forRoot(routes)]  
})  
export class AppRoutingModule { }  

Step 2: Add <router-outlet>to app.component.html

<nav>  
  <a routerLink="/">Home</a>  
  <a routerLink="/about">About</a>  
</nav>  

<router-outlet></router-outlet>  

• Clicking on Home (/) will load HomeComponent inside <router-outlet>.
• Clicking on About (/about) will load AboutComponent dynamically into <router-outlet>.

Using Multiple <router-outlet> for Nested Routing

If your application has a three-level navigation structure (Parent → Child → Grandchild), you can use multiple <router-outlet> elements.

Example: Parent-Child Routing

const routes: Routes = [  
  {  
    path: 'dashboard', component: DashboardComponent,  
    children: [  
      { path: 'profile', component: ProfileComponent },  
      { path: 'settings', component: SettingsComponent }  
    ]  
  }  
];  

dashboard.component.html

<h2>Dashboard</h2>  
<a routerLink="profile">Profile</a>  
<a routerLink="settings">Settings</a>  

<router-outlet></router-outlet> <!-- Child items are mounted here -->

• Enter /dashboard/profile, and DashboardComponent will be shown.
• ProfileComponent will be displayed inside the <router-outlet> inside DashboardComponent.

Named <router-outlet>for Multiple Views

You can use named outlets to render multiple views in different containers.

<router-outlet name="primary"></router-outlet>  
<router-outlet name="sidebar"></router-outlet>  

This way, you can create layouts with multiple views.

<router-outlet>is essential in Angular for navigation and dynamic component loading. It enables the creation of complex applications with nested routes, lazy loading, and multiple views.